Finally Microsoft has released the SPDisposeCheck tool for SharePoint Developers. When you building custom applications involving the SharePoint API you need to keep in mind that their are two objects you need to worry about handling memory usage. After using SPWeb and SPSite you need to call the Dispose() member or memory is eaten by your system which could end into performance issues on your whole system.
With this tool created assemblies can be checked on these objects if calls to Dispose() are made. A handy tool, but still as developer you need to be carefull yourself and always check your Dispose() calls on these objects
References:
Best Practices: Using Disposable Windows SharePoint Services Objects
Best Practices: Common Coding Issues When Using the SharePoint Object Model
Roger Lamb's SharePoint Developer Blog