According to the Michael Martin at the GoogleAndBlog, a T-Mobile support rep has made reference to a T-Mobile plan to send out free extended batteries and matching rear covers to users that have bought a T-Mobile G1 from the company.  Battery life has been one of the major issues for most users, and the supposed new battery would, at 1400mAh in capacity, offer just shy of 22% additional battery life.

Martin quotes a T-Mobile rep as saying:

“After everything they did, and the amount of time put into this (extended battery) project, I doubt they would scrap it now.”

Sounds plausible to us, but I’m not sure how much of a bulge it would cause in the rear cover, and if 22% more juice is going to make that extra size worth it.  Assuming any of this actually pans out, of course.