AutoSearch Mobile, like its full-featured — and more expensive — PC and Mac version, makes it a snap for on-the-go recruiters to search much of the public (and some of the private) web without having to know all that complicated Boolean stuff.

That sound you just heard was the collective gasp of every sourcer in the world sucking the oxygen from the atmosphere. So that we may all resume breathing, let me hasten to say every recruiter ought to know how to write a Boolean search string.

But when you’re on the train commuting to work, or on the L circumnavigating the Loop or in a carpool on the 101 freeway, it’s way easier to use a pulldown menu and a few keywords to look for candidates for that new req. Behind the scene AutoSearch Mobile converts your keywords into Boolean, then searches the web for public resumes and a handful of key business networking sites for matches.

The results can be scrolled, the first few lines of the resume showing. Find something interesting and you can expand it to read more. You can email yourself the search results right from the app.

Lori Fenstermaker, principal of AutoSearch, told me the mobile search is slicker to see than to describe. “People are usually quite surprised,” she said, when they actually try it. “It’s really easy to use.”

Like the full version, AutoSearch Mobile will find matching candidates who have posted public resumes. It also searches LinkedIn, Twitter, Jobster, and ZoomInfo. Unless you have a connection, you’ll need to do a little sleuthing to track down a candidate from those sources, but then that’s why it’s called sourcing, and not compiling.

Fenstermaker sort of stumbled into the software business. The Grand Rapids, Michigan, resident was operating a boutique talent acquisition firm when she took a class in online sourcing.

“Pretty soon I found myself spending more time writing complex Internet search strings than I was calling candidates,” Fenstermaker admits in a post on the AutoSearch website. She turned to her husband who owned a software development company and AutoSearch was born.

It proved so popular with her search clients that they began asking to license it. Now AutoSearch is a separate company and, says Fenstermaker, it occupies most of her time.

AutoSearch for the PC or Mac has plenty of competition. There’s eGrabber and TalentDrive among others.

However, mobile search utilities are still relatively rare. Most of the leading job boards have iPhone applications to help job seekers search listings. But the only direct competition for AutoSearch Mobile I’ve found is Search On the Go, which is $9.99 in the iPhone store. It’s interface isn’t quite as simple, but it does save and display search strings, a feature that AutoSearch Mobile lacks. Both apps access only a single, generic search engine: Yahoo for AutoSearch Mobile, Google for Search on the Go.

The Facebook app comes from LinkUp, one of the second-tier job search engines. It’s owned by JobDig, which operates a traditional pay-to-post job board and an inexpensive on-demand ATS called JobDig Tracker.

If your company career site is one of the 22,000 indexed by LinkUp, then installing “Current Jobs at Our Company” will automatically update your company’s job listings on Facebook every day. The first five jobs are free. Any more than that and you’ll have to pay $39 a month.

In either case, LinkUp must be indexing your career site. Check LinkUp to see if that’s happening and if you don’t find them there, then you have to contact the company.

As much of a time saver as this app can be, if you don’t work your Facebook presence then it really won’t make a difference. Simply posting jobs to a friendless Facebook site is a waste.

JobDig CEO and president Toby Dayton makes that point himself in a blog posting that praises Hyatt Hotels for its community-building efforts. Now it happens that Hyatt has installed the Current Jobs at Our Company app and, presumably, is paying JobDig $39 a month for the more than five jobs capability.

But Dayton is right about the personal effort Hyatt is making. Take a look at the comments on the Wall and you can see there’s a thinking person behind the company’s comments. As he put it in his blog post, “there is a real dialogue going on between job seekers and people within Hyatt.”

Now, there are plenty of jobs apps available for Facebook. There are apps for users interested in security jobs, and apps from CareerBuilder for jobs of almost every type, and Indeed, which has a new mobile app we’ll get to in a moment, has an app to find jobs where your friends work. But as far as I can tell, LinkUp is the only app developed specifically for recruiters. And no, I’m not forgetting the Jobvite or Force.com apps. They are aimed at getting referrals by leveraging their employees’ Facebook relationships. Plus they cost a boatload.

Indeed, which never seems to sleep, has the #1 most popular free business app for the iPhone and iPod. And, to give credit, where credit is due, CareerBuilder is #5 on the list.

While everybody always wishes for some feature more than the product has, Indeed’s app is rated a bit higher than CareerBuilder’s. Of course, CB released its app 14 months ago, pioneering, if you will, mobile search in the U.S. Indeed released its iPhone search in March, including some features CareerBuilder’s reviewers wanted.

Soon, jobseekers with an Apple iPhone (the epitome of techno-cool) can search for a job on their phone as easily as on their MacBook. And actually, it might even be easier, since CareerBuilder uses the iPhone’s geolocation to identify your city. All you do is enter the relevant keywords and up pops a list of jobs. Scroll the list, jump back and forth, narrow the list with more keywords or change location, should you decide Las Vegas would be more fun than Topeka.

Once you find a job that interests you, select it and CareerBuilder emails you the link so you apply when you get home. More than one job of interest? Add it to your favorites and you get sent the whole list.

Check out the online demo to see for yourself how it works.

CareerBuilder’s Jennifer Grasz tells us the service will launch any day now and when it does, all jobs on CareerBuilder.com will be accessible. Employers don’t pay extra and jobseekers pay only for the data transfer, according to their ATT contract.

Although iPhone users represent a small percentage of mobile users in the U.S. (in part because of Apple’s deal with only one carrier, ATT), they are among the heaviest consumers of mobile content. How extensively they will use the new service is anyone’s guess. “We are getting in the door early to tap into the potential of a user base that is expected to grow at a substantial rate,” Grasz says.

Mobile job searching and even applying is more common in other parts of the world, especially in Asia where cell phones are more common than landlines and personal computers.