CCleaner works without any problems in Windows 7. It is always recommended that you review the results found in any registry cleaner to make sure that they are safe to delete, but I have never had CCleaner find anything that wasn't safe yet though.
What's New about CCleaner:
Redesign of Cleaner results panel.
Added support for Opera 10 Beta.
Added support for Safari 4.0.
Added search to Uninstall tool.
Added search to Cookies screen.
Improved User assist cleaning in Windows 7.
Fixed bug in OpenOffice cleaning.
Fixed IE8 SuggestedSites.dat cleaning support.
Fixed UI bugs
