Google Unveils First Android Phone
The problem is that in order to get the phone, you need to sign a 2 year contract. As part of the contract, you have to agree to a credit check.
The bottom line that it will be quite easy for T-Mobile and/or Google to associate all of your most personal information (real name, address, SSN, credit history) with all of the information that Google already collects (your search history, email/IM contacts, location).
A paranoid person might think that the whole reason for Google releasing Android is so that it can get a bullet-proof correlation between a person's online and real life identities...