The X18 is a 1.8” model with capacities up to 80GB at launch. The X25 has the same maximum capacity currently in a 2.5” form factor. The drives will feature 160GB capacities later this year. Both of the drives are based on MLC flash, and will be sold starting at around $595. Pricey, yes – but when SSDs first hit the market, even a 16GB unit could be that much. You can read more in Intel's press release.
Intel is still planning the release of the more reliable SLC flash based drives for server and storage environments.