Google Tasks on iOS

The only gmail integration is that I will open a Safari when you click "related email" link. If you happen to be logged in, most of the time it will open the right email on the iPhone/iPod (this is currently not working for iPad thought). To answer your question directly, there is no Gmail offline or anything like that.

EDIT: now that I think of it, I could copy the subject line of the related email into clipboard, and you could then use iPhone's built-in search. would that help?