1) There is now a grim reaper - by default this will cull any
scheduled events that are delivered later than a set time (defaults to
3.25 seconds). If you want to turn off the reaper set the reaper time
to 0. By default the reaper will not cull callbacks, although you can
set it to do this by checking the appropriate flag. You can set this
stuff in impromptu preferences.
2) For those doing movie capture you can now capture in a compressed
format. Check the capture-movie help for details.
3) AudioUnit views should now resize properly (sorry about that :-)

Impromptu now supports apple's standards keybindings. Check in the dmg file for the DefaultKeyBinding.dict file. This file will need to be installed in ~/Library/KeyBindings/DefaultKeyBinding.dict. If the directory ~/Library/KeyBindings does not exist just make it yourself. Take a look here for an explanation of how keybindings work and make sure you open DefaultKeyBinding.dict in your favorite text editor.