I'm pleased to announce that F# 22.214.171.124 is now available from the Microsoft Research Downloads site. I'll post the release announcement and some additional notes in a follow-up shortly.
This was the version that was running in our booth at TechFest 2005, the truly amazing event run each year by our research organisation (see some press coverage of the event). For two days Byron Cook, Satnam Singh, Gavin Bierman, myself and others presented the basics of "mixed functional/imperative/object-oriented programming in the context of .NET" to hundreds of Microsoft staff and visitors.
Some old-time functional programming hands were surprised at how we were able to communicate the basic concepts in a compelling way. One thing I noticed was that having the results of type inference displayed in Visual Studio made a big difference - suddenly the code was alive! (Or, a little more plainly, the readers were relieved of the burden of having to mentally re-construct the types themselves) Another thing was that we continually pushed on the point that you simply write fewer "classes" (i.e. type definitions) when using F# - many simple classes, interfaces and delegate types just disappear, due a combination of inner function definitions, discriminated unions, function types, object expressions and record expressions.
Finally, it really helped to have groovy demos involving DirectX, and nothing could quite beat Andrew Phillip's pulsating stochastic life simulator, which really looks like it is alive. Like many other good F# applications this program is written in cross-compiling OCaml and F#, and has a GUI interface written in F#.