Microsoft's Enterprise Search website contains information on search products, including FAST ESP. You can also read about the Enteprise search solutions - Enterprise Search for Internet Business and Enterprise Search for Business Productivity here.

Speaking of the amount of technical content on FAST, I browsed through and found and almost all content on existing FAST Search ( website can be found here plus some new content.

Homepage on FAST has lot of content including key benefits, capabilities and links to brochure, datasheet, case studies, product sheets on FAST ESP and FAST ESP Add-Ons. There is also information on FAST Solutions Services and Support Offerings:

Microsoft Enterprise Search Blog also some interesting posts like the recent Search and Natural User Interfaces series - Part 1 and Part 2.