This morning T-Mobile announced the upcoming G2 Android smartphone and posted a teaser site for the device.  The T-Mobile G2 will be the first handset from the wireless carrier to work with its growing HSPA+ “4G” data network.

Additional details about the G2 were absent the announcement. We know that the G2 will replace the aging G1, which was the first Android-powered phone on the U.S. market.  We also assume that, like the G1, the T-Mobile G2 will be built by HTC.

T-Mobile announced in July that its HSPA+ network upgrades would be deployed to serve 185 million people by the end of 2010.  Under perfect – but likely never-to-be-seen – conditions, the HSPA+ network can provide up to 21Mbps download speeds to handsets and wireless modems.

We’ll post more information on the G2 as it’s made available.