I just added the new "upcoming features" page. It lists all changes and new stuff that is already available in the latest cutting edge release:
- Gmail 2 support
- Mailplane URLs
- Background account notifications
- Account nickname and re-ordering
- and much more...
What is the cutting edge release anyway? It's the upcoming Mailplane version, it's where the new features are added, tried and tested. But, as much is added or changed it may be less reliable than the current stable release.
If you like to try it anyway: instructions can be found in the extended and improved FAQ section.