SharePoint 2007 and WSS 3.0 Dispose Patterns by Example

It is a good practice to make sure your solution is free of memory leaks.

Check this out :

http://blogs.msdn.com/rogerla/archive/2008/02/12/sharepoint-2007-and-wss-3-0-dispose-patterns-by-example.aspx

Use the SPDisposeCheck utility to examine your code.

Further references on this subject

http://msdn.microsoft.com/en-us/library/aa973248.aspx

http://furuknap.blogspot.com/2009/08/spdisposecheck-in-visual-studio.html