The SQL Server adapter I've been working on for the past 6 months or
so now passes all the tests in rails 2.2 and 2.3 for all SQL Server
versions. It is also Ruby 1.9 compatible, UTF-8 support, etc. Tons of
info can be found in the README on github.
I have also just recently published the de facto "activerecord-
sqlserver-adapter" gem name on RubyForge too.
Lot's of details can be found on our Google group.