The T-Mobile G1 (see my full review) is currently the only Google Android device on the market and is available only from T-Mobile. There are a couple of rumors surrounding the G1 that I am trying to verify with my T-Mobile contacts. The first one concerns a possible US$20 price drop for the G1 and the option to purchase one and activate only a data plan for US$34.99 with no voice plan. The second rumor is that T-Mobile is sending new batteries to current G1 owners.
The data only option for the G1 makes sense since you can do the same thing with the T-Mobile Sidekick and both of these types of devices are heavily focused on data consumption and text-based communication. With the G1 you can stay in touch via text messaging, email, and instant messaging. If a data only option is available, it may make the G1 a bit more compelling for teens who seem to text much more than actually talk on the phone today.
Apparently, T-Mobile may be sending out a 1400 mAh battery to replace the current 1150 mAh battery on the G1. This gives you a 22% increase in battery capacity that should also give you a bit longer battery life. This higher capacity battery also fits inside the same compartment with no new back needed to hold it in place. One person has reported receiving this battery and has a photo of the replacement. It is a bit strange though that only one person reports receiving the battery so far and this may just be a battery replacement sent to someone as a result of a called-in complaint.
If you want a real extended life battery for your G1, then you might want to consider the Boxwave ElectrSpan battery that has a whopping 2400 mAh capacity. This does come with a new back black cover. I am considering this myself because I can't get through a full day with my G1 at the moment.