It is a perl script that uses 'aspell' [
link]. The only thing I modified with vBulletin was adding the button that sent your message to the perl script via javascript, which in turn sent back the corrected version, and placed it back into vBulletin. Probably very easy to add on to phpBB2, if of course you can install aspell on your server.
Next task: find out how to add words to the dictionary; or at least use 2 dictionaries. (1=english, 2=FIRST)
