Juno is coming - This year, lets see if we can stay compatible. There should be a compatibility layer so unless we use changed internal API's we should be fine.
If you have a plugin that does not compile/work then we should investigate what options we got - trying to avoid having to maintain two forks!
Eclipse migration tips: http://dev.eclipse.org/viewcvs/viewvc.cgi/org.eclipse.platform.doc.isv/porting/3.8/incompatibilities.html?revision=1.1&view=co
(not sure that being empty can be all true)
WTP help for old friends: http://wiki.eclipse.org/New_Help_for_Old_Friends_VII
JBIDE-8624 for last years Indigo move.
Please link related Juno to this issue and if we find issues please outline the fix and if relevant relate eclipse bugzilla references.