Your first alert to potential problems can happen right out of the gate—before you even complete your upgrade to Lion. During the Mac OS X Setup Assistant phase of installing Lion, you may get a warning of “incompatible software.” Identified items are moved to an Incompatible Software folder on your drive.

This early warning system will not ferret out all software that hiccups under Lion. Rather, as , it focuses on apps that “can quit unexpectedly or cause other issues.” It especially seems to focus on software that runs in the background—such as the versions of Default Folder X and TotalFinder cited in the figure above.

You should respect the Installer’s wisdom. Don’t bother trying to re-enable or run the disabled software. If you do, you will likely get another similar warning. A better solution is to check with the vendor for possible updates. Indeed, a Lion-compatible and are now available.

As you’ve probably heard by now, . This means that you won’t be able to launch older Mac applications designed to run on Macs with PowerPC (as opposed to Intel) processors. If you attempt to launch one of these Rosetta-dependent programs from the Finder, you’ll be greeted with a warning, as seen in the figure below.

The PowerPC app that’s been getting the most publicity in this regard has been Quicken. However, many other familiar applications are suffering the same fate. For example, if you still use the Rosetta-dependent , it will not work in Lion (Office 2008 and 2011 are Intel apps and should work fine).