No, not a full list available yet. We'll be releasing the changelog when the release is available. The biggest change (the reason it's called 4.0) is due to an updated authentication scheme which will be required by Facebook later this year.
We come out with new big releases every 2-3 months, with minor releases (bug-fixes or minor features improvements) every few weeks, just so you know.
If there's any issues you're running into right now though, feel free to let us know about them, and we'll let you know if we're aware of them or planned to be fixed in the next release.
Thanks,
Alex