The T-Mobile myTouch 4G Slide is available at their online store for $199.99 after instant and mail-in rebate card.  Required for mail-in rebate you must be a new activation customer with a 2-year agreement and bundled data calling plan or web service of $20/mo. or more.

Carrier: T-Mobile
Retail Price: $499.99
Hot Features: 4G, dual-core 1.2 GHz processor, 3.7" touchscreen with slide-out QWERTY keyboard, access to Netflix