I’ve heard this one a lot lately from many people, so I felt it was time to share more broadly.  While there is no way to do this in the UI in TFS 2010, there is a registry key that we added late in our release cycle to allow users to configure the default work item association.

To make “Associate” the default action (instead of “Resolve”), set the registry key “HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\10.0\TeamFoundation\SourceControl\Behavior\ResolveAsDefaultCheckinAction” to “False”. 

FWIW, in our next release, we’re fixing this experience so that you won’t need to hack the registry to change the behavior.