Any time frame for CF 3.5 support?

Compact Framework 3.5 can use CF 2.0 assemblies, so you can use the SDF with a 3.5 application today.  The next release of the SDF will still targeting CF 2.0 but running under Studio 2008 so you'll get designer support, etc for Studio '08 (which is probably what you meant).  We have no definite release schedule yet for that.

On 2007-11-13 Neil mentioned early 2008:

http://community.opennetcf.com/forums/p/10133/63991.aspx

On 2008-03-07 Neil talked about 60-90 days: 

http://community.opennetcf.com/forums/p/10546/64892.aspx 

So I hope there is a kind of vague chance to see it before Q3/2008...

And now you see why most companies won't commit to a release date unless they have a specific schedule, and even then they often don't announce.  We know people want it, and we want to get it out.  We have several things we want to do with it for the '08 compatible release, and we've got a lot of other things going on, so things tend to slip when that happens.  For those reasons I won't give any time suggestion - I'll simply repeat that we know people want it and it's certainly one of our goals to get it out as soon as feasible with the quality we think people deserve.

In the meantime, the SDF can be used for 3.5 projects, you just lack the nicety of designer integration, integrated Help, etc. 

I just wanted to mention that the team already talked about this and that there is a chance to see the final product in first half of 2008 (and that's not that far away ;)).