The drive uses an undisclosed third-party storage controller and firmware that have been tweaked by Western Digital itself for improved performance. Although they wouldn't reveal who's behind the controller, Anand did some digging around and identified its internals as JMicron's JMF612 (same as Crucial's Reactor series). The controller features a garbage collection routine and supports TRIM and Native Command Queuing, which is to be expected of modern SSDs. Western Digital won't be offering a manual TRIM tool for non-Windows 7 systems, though.
The SiliconEdge Blue uses a 3Gbps Serial ATA interface and can reportedly sustain reads at 250MB/s and writes at 140MB/s -- maximum write speed is 170MB/s. There's 64MB of DDR2 cache memory and Western Digital claims the drive can process 5,000 IOPS with random 4KB reads and writes. Unfortunately performance tests show the SiliconEdge Blue is no match for Indilinx-based or Intel SSDs, yet it is more expensive than both.
The drives will be available in 64, 128, and 256GB capacities with suggested retail prices of $279, $529, and $999, respectively. (Note: as mentioned in the comments, Newegg.com has them for $249.99, $449.99, and $799.99) Intel's significantly faster X25-M G2 160GB on the other hand can be had for $429, while OCZ's Vertex Turbo 120GB are selling for as little as $360 these days.