Yesterday, Microsoft/FAST announced at the FAST Forward conference in Las Vegas the immediate roadmap of the FAST ESP (Enterprise Search Platform) product line. Also see what CMS Watch writes about the topic.
Office 14
The main news is that ESP will be included in Office 14, to serve as the advanced/extended search server of Sharepoint. It has long been a problem that the Sharepoint Search Server can only handle about 50 million documents, and by offering the FAST-based extension, this will be extended to almost infinite number of docs, as well as enabling some features which Sharepoint did not have as well (faceted navigation being one of them). The product will be more limited than the full-fledged ESP in that you cannot tune as many parameters. Much of the middleware and administrative components of ESP are stipped out and replaced with Windows/Sharepoint/MSSQL components, for a tighter integration.
But Office14 will not ship before 2010, so as a gap-filler Microsoft will sell ESP for Sharepoint for as little as USD 25.000 per server, which is a fraction of the typical license cost for such a system. This product is basically the same as today’s ESP, but if you intend to upgrade to Office 14 Extended Search, you better not use all the features of ESP, but stick to the recommended customization options which are compatible with the coming Office 14 search.
FAST Search for Internet Business
The second product announced is “FAST Search for Internet Business”, intended to fill the needs of the typical existing FAST customer within site search or e-commerce. Even the Linux versions of this product will be developed and maintained alongside the Windows versions.
A good question is how MS/FAST is going to maintain all these code bases going forward. I’d expect a consolidation sooner or later, and perhaps also an end-of-life announcement for the Linux platform support within the next 5 years. But that will only be speculations anyway 
