I just got an 8800 and used it for a week before I started looking for the spell check. It is apparently not there. Not in the applications list as it is with my Curve. Talked to my BES administrator and he is puzzled, too.
8800 does not have a built in spell check. I use LexSpell. Works great. BBSpell is another I think. Check the 3rd party section. Don't know if OS 4.5 adds it or not.