I know currently Spotlight on iPhone OS 3.0 does NOT search the body of emails, however I'm curious if anyone who has played around with the 3.1 betas knows if that's changed? 
Before you ask, yes, I've searched the forums and have not come up with an answer to my question, hence, why I'm asking here!
Before you ask, yes, I've searched the forums and have not come up with an answer to my question, hence, why I'm asking here!