On April 24, 2002, NeuStar, Inc. (a division of NeuLevel, Inc.) went live as a consumer-level registry for .us domains.
Only individuals and businesses located (or represented) in the United States can register .us domains.
The "landrush" period for pre-registration began in January, 2002. Approximately 45,000 .us domains were pre-registered by about 200,000 people, across the approximately 200 United States-based domain name registrars that are a part of the NeuStar reseller program. Domains with multiple requests for registration were placed into a lottery and registered to one random registrant that had requested the domain, or to the domain's copyright holder (if applicable). NeuStar charges $15.00 USD per year of registration, with a 2-year minimum.
The previous .us format (such as .tx.us) remains but can only be used by those institutions for which it was intended, like schools/colleges, public libraries, state governments, etc.
The only practical use I can think of for this TLD is the domain "join.us," which could be made into a fan page for Slayer, or something. If NeuStar/NeuLevel handles .us like it did .biz, .us domains will most likely be little more than fodder for spammers who can't think of a .com or .net domain that isn't already taken.