I just upgraded Eclipse to 3.4 (Gandymede) since the latest upgrade to Flex Builder included support for Gandymede. I did my typical install by extracting the Gandymede tarball and then installed Subclipse through the Software updates (now in Help -> Software Updates...).
It looked like everything installed okay but then when I tried to do an update in an existing project I got an error:
"Unable to load default SVN Client"
The key is to include the
SVNKit Adapter JavaHL Adapter when you install Subclipse:
Hope that saves some people some time.
NOTE: Thanks to Mark for pointing out the recommended usage of JavaHL instead of SVNKit!