We have discussed the SharePoint 2007 SPDispose tool here before. A new version is now available with SharePoint 2010 support and a Visual Studio add-in.
In addition to dispose guidelines they have also added rules on when not to Dispose. For example you do not want to dispose your SPWeb en SPSite objects in your SPContext.
More information can be found on http://blogs.msdn.com/b/rogerla/ and on the SPDispose codeplex page.
Download is available on here on the Microsoft download site.