According to this page, SQL Server 2008 Express Edition with Advanced Services includes Fulltext search:
However, I downloaded it, ran it, and I see no sign of it. There is no fulltext service, and when I try to do anything to do with fulltext it says
Msg 7609, Level 17, State 5, Line 1 Full-Text Search is not installed, or a full-text component cannot be loaded.
When I run the re-installer to add features, I still don't see it. It claims I have everything installed.