We recently published a fix for the following problem:
You create a deployment project for a web application in Visual Studio 2010, set the deployment property RestartWWWService=false and deploy to a Windows 2003 server. http://msdn.microsoft.com/en-us/library/22f9106b.aspx
In this situation the w3wp.exe process will still be recycled even though the RestartWWWService is set to false.
The fix is available at http://connect.microsoft.com/VisualStudio/Downloads/DownloadDetails.aspx?DownloadID=32285 and should only be installed on development machines if you experience this problem.
Have a good one,