Windows: There's no reason to rely on individual applications to tell you when they need an update, when you've got a handy tool like TechTracker.
You'll need to create a free account or use Facebook connect to login to CNET and download the TechTracker application. Once downloaded and installed, finding the out of date applications on your system is as simple as running the application. TechTracker compares the software versions of your applications to the vast database of applications at Download.com and shows you a list of which applications need to be updated and a link to Download.com or the publisher's site where you can download the update.
You can also tell TechTracker to email you when a new version of an application you have comes out, so you'll get an email update before the next scan even takes place. TechTracker is freeware and works wherever Windows does.