Daniele over on hubFS has been doing interesting things with AutoDesk and F# in the last few days. Take a look at this link:

How to write an Autodesk Inventor Add-In using F#

Coincidentally, Kean Walmsley has written his first AutoCAD application using F# and has just followed up with A mathematical F# application integrating with AutoCAD via .NET which amazingly embeds one of the F# DirectX demos directly into AutoCAD!

I've always thought tools and domains such as these are a perfect match for functional programming, and it seems Kean and Daniele like what they've seen so far. The synergy here via .NET and F# looks great.