RIM's BlackBerry Bold 9900 will be released on August 31 nationwide on the T-Mobile network. It will be available at T-Mobile stores and at select third party dealers and retailers. For business customers, T-Mobile is holding a special exclusive pre-sale of the device on Wednesday.

The BlackBerry Bold 9900 is RIM's flagship phone and its answer to the 4G world. 

It's the thinnest Blackberry smartphone ever at only 10.5 mm.  The phone features both a touch screen and Blackberry's iconic QWERTY keyboard.

It will run the new BlackBerry 7 operating system, which sports "a next-generation BlackBerry browser with a significantly faster, more fluid Web browsing experience that is among the best in the industry."

"Running on America's Largest 4G Network, the BlackBerry Bold 9900 helps make life truly mobile - all at 4G speeds," said T-Mobile in a press release.

The BlackBerry Bold 9900 will sell for $299.99 after a $50 mail-in rebate with a 2-year data plan with T-Mobile.  LA Times pointed out that this is more expensive than the 3G BlackBerry Bold 9930, which will sell for $249.99 under a comparable plan with Sprint and Verizon.

Cnet's Roger Cheng called the $300 price tag "just plain crazy."

"When the bar for a vast majority of smartphones--even high-end ones such as Apple's iPhone--is set at $200, and you go over, that's a problem. For RIM, the premium price is going to be a critical problem as the company attempts to claw its way back to the top of the smartphone hill," wrote Cheng.