T-mobile confirmed today with me that MicroSD HC 16gb cards and 8gb will work with Tmobile G1 (Google Phone). You can order both cards on Amazon estimate cost is $120 for 16gb and about $25 for 8gb. My suggestion is that you order 8gb now and wait about half a year and buy 16gb for same price you bought 8gb for. Personally I think price for 16gb Microsdhc card is a bit too much right now.