Check Integrity script for blender 2.5
This is my first script adapted for blender 2.5. It was a bit of work to understand all the differences but I think the next ones will go faster now. I'll wait for the new blender project tracker to be up then I'll submit it there.
The script checks a mesh object and selects all edges that are not manifold (that is, that don't have exactly 2 faces connected to them). In other words, a manifold mesh is a mesh that can be converted to a perfect solid (no holes, and no face that has no inside/outside). After running the script on the active object, enter editmode and the bad edges will be selected so it's easy to find and fix them.
Install the script via the addon manager, it will then be available in the "Object" menu.