Just a bit of heads up if you're experiencing application crashing and "PermGen space" errors when using Eclipse with the latest Java 6 update 21 release. A minor rebranding change by Oracle has unexpectedly caused a bit of a headache for developers.
You can find out the full details on InfoQ in Eclipse and Java 6u21 problems along with a link to a very simple workaround fix. Oracle have regressed the change for the next Java 6 release and won't implement it again until JDK 7.