SUPERTALENT JUST PUT out a 512GB SSD, claiming to be the first one commercially available. The capacity differential between the magnetic and flash has shrunk to only a factor of four.
The new MasterDrive RX comes in 128, 256 and 512GB capacities, and hits speeds of 230MB/S read, 160MB/S for the biggest version. The 128 and 256 use SLC flash instead of MLC like the 512, so write speed is upped to 200MB/S. It looks like the 230MB/S number is controller limited.
The drives are 'RAIDed', as is the current fashion, so you get a lot of speed for less money, but pay for it a little in minimum block size, but that is bearable. In any case, they cost about $1,500 for the 512GB version, but we have it on good authority that they will knock $25 off the top if you buy in quantities of 1,000 or more.
Read all about it here. µ