I heard at the p2 BOF at EclipseCon that you could use your profile as a p2 repository. This sounded like a cool way to take an Eclipse setup that you've customized and replicate it into a new install. Granted there may be better ways to do this with shared bundle pools and what have you, but lets set that aside for a moment.
Since 3.5M7 is out, I decided to take a stab at cloning my 3.5M6 setup into 3.5M7. I had installed SVN and DTP along the way so I was hoping this would take the pain out of having to go out and re-provision those items from the web. (Of course I should probably upgrade DTP to the M7 version, but again, lets set that aside.)
1. Unpack 3.5M7 into a new directory
2. Launch it
3. Help -> Install new software...
4. Click the Add button to add a site
5. Click Local to browse
6. Select the .profile directory from previous install. In my case, file:/C:/eclipse3.5M6/p2/org.eclipse.equinox.p2.engine/profileRegistry/SDKProfile.profile/
7. Give it a name, hit OK
8. You should see all your plugins from that profile. You might need to uncheck "Show only the latest versions" and "Group items by category"
9. Check all the plug-ins you want (sadly, I couldn't find an action to mark multiple at a time)
10. Finish the wizard and restart the platform
And you're done! Awesome. Thanks to Simon Kaegi for implementing this.