The website Cowcotland released a test of the 3.5" OCZ SSD Colossus. This is currently to our knowledge the only drive available in this format. It offers storage space of 120, 500 and soon 1 TB capacity. The smallest model was tested. Figures clearly indicates that such drives can deliver high performance levels, up to 260 MB/s. It is however not so good for random writing tasks (less than 128 KB). This could be linked to the way the drive is designed with a RAID 0 volume with 2 controllers. Last but not least, below is the xBench results of the 500 GB Colossus installed in a Mac Pro:
Figures are much better that one can be obtained by a disc-based HD, even a 3.5" SAS.