T-Mobile G1 user guides found on support site
It appears that the guys over at TmoNews have been busy. A few of their minions have located the Getting Started and User Guide PDF file links on the T-Mobile support website.
The getting started guide is 48 pages long, while the full user guide/manual is 141 pages long. If these two PDFs won’t keep you busy for a day or two, then I just can’t help you.