Is there an iPhone Application (app) available?

Yes! USAJobs has a search application available. It's designed for both iPhone & iPad.

For basic information and some screenshots, please visit http://apps.usa.gov/usajobs.shtml; or http://itunes.apple.com/us/app/iusajobs/id386297670?mt=8 for more information on features, more screeenshots, and download instructions.