I've put up an official beta of Acorn 3.2 on the latest builds page. This release is mostly about bug fixes, including some crashers that have been plaguing Acorn for a while now (check out the whole list here).
Acorn 3.2 is also quite a bit faster if you're working with big images (and by big, I mean 10 megapixels or more). In my tests I'm finding these improvements:
Cropping is up to 2.5x faster. Applying filters is up to 9x faster. Performing multiple rotates in a row is up to 6x faster. Auto Levels is 8x faster.
And the larger your image is, the bigger the difference in performance you'll see.
For the curious, I tested on 3 machines- a 2006 Mac Pro (MacPro2,1), 2011 11" MBA (MacBookAir4,1), and a 2010 iMac (iMac10,1).