Security improvements and lots of fixes
The major change is that PyBitmessage now supports TLS encryption among compatible nodes. This improves security. Another security improvement is that the SQLite database now zeroes deleted blocks.
The bundled executables (Windows and OSX) now include a working C implementation of PoW, which should make sending messages more efficient. The executables now also include translations, so if you use PyBitmessage with these executables, you'll be able to change language.
You can also benefit from several bugfixes of the user interface, and other small updates, like the ability to blacklist senders directly from the message or to see the sync status in the network tab (it shows how many objects are left to be synced).