The MIST board had many improvements over the last few months. The latest changes include STE and MegaSTE support. Current work focusses on the STEroids mode which is planned to bring the boards speed on par with the Atari TT. After that some of the TT video modes (at least 640x480x16 colors) are planned.
For more details on the current state please check out the MIST section on atari-forum.com