It took a bit longer than expected, but thanks to the great patience Doron, Aaron and bz had reviewing the last critical bug, it is finally here:
The XForms AddOn for Firefox 3.5. Download it now while it's fresh :-)
The XPI contains binary components for Windows (32bit) and Linux (32 and 64bit).
Remember: this is an experimental development snapshot, so don't be surprised if it kills your cat. But it should still be more stable than the previous release version, as we fixed some crash bugs.
I also added a bit of documentation on how to build Mozilla XForms from source at the Mozilla Developer Center.