John Arthorne announced on the e4 mailing list that the first drop of Eclipse SDK 4.0 is available. This is Eclipse e4 which host itself. To give it a test spin just download. the right version of your SDK from:
If you find issues please enter a bug report.
Please note that the SDK download does not include the e4 wizard to create new Eclipse e4 projects. You have to do it the hard way.