The intensively rumored T-Mobile Project Dark is now official. T-Mobile published the new Even More and Even More Plus plan options on their web site.
Under the new T-Mobile Even More Plus plan you do not need an annual contract. The plan options under Even More require a 2 year contract requirement. For that you get phone discounts.

Under Even More Plus the unlimited data plans (Talk+Text+Web) start at $59.99/month, which is nice. If you do not have a cool phone yet you need to pay for instance $499.99 of the myTouch 3G or $549.99 for the HTC Touch Pro 2. The T-Mobile Even More plans still look weird to me on the web site as they do not offer data, but leaked flyers confirm that the unlimited data plan (Talk+Text+Web) will be priced at $99.99 to directly match other carrier's plans, like Sprint's all-you-can-eat plan.

Overall only Even More Plus is a new rather unique offer in the United States. If you hate contracts this is for you. T-Mobile also offers to finance new phones via their FlexPay option.
More details on the T-Mobile site.