The spell checker does the same in FireFox 2!
Er, no, it doesn't. Let me test it, and spell check using FF2:
Wlel, I thuoght that it wsa verry awsom.
Firefox's spell check returns it as:
Well, I thought that it was very awesome.
OMG, ITS AWESOME
.
EDIT: Oh, oops, I thought you meant the built-in spell checker (built-into Firefox 2) >.<. Sorry, yeah, Spell Check on ZFGC doesn't work.