I've been working on migrating to Eclipse v3.6.1 x64, but was having a ton of issues getting Subversion/SVN support working in Eclipse. I prefer using Subclipse, so it was my goal to get that up and running because I'm used to the interface.
I originally tried using SVNKit, because I wanted to use native libraries. However, when I tried to use the SVNKit connector, every single time an SVN operation would occur it would prompt me over and over for my credentials—like it was saving them (although it was updating the .keystore.) After getting frustrate with this, I decided to just use the JavaHL libraries.
If you're using Eclipse 32-bit, then everything you need is included with the distributed versions of Subclipse. Since I'm using the 64-bit version of Eclipse, I needed to download Slik's Subversion v1.6.16 (x64). So, I closed down Eclipse and install the 64-bit client. I verified that everything was working correctly by running the javahltests.jar.
However, after restarting and configuring Subclipse to use JavaHL, I started experiencing issues with Eclipse hanging up. I'd constantly get messages like "Building workspace"—which would stay at 0% and never progress. Switching back to SVNKit was working, but the constant credential checking was driving me crazy. So, after lots of researching, I finally found a thread on authentication issues on the SVNKit mailing list. Turns out I am using NTML and Basic authentication on our server and that was causing an issue with SVNKit.
The fix is to edit your eclipse.ini file and add this line somewhere after the "-vmargs" line:
Depending on your configuration, you may need to tweak the order of the methods, but as soon as I restarted Eclipse with this line in my eclipse.ini everything started working like I expected.