We cannot hold back progress of the project taking advantage of new things in 3.5 .NET, its better if you upgrade to 3.5 .NET or you will have to go through the same process to make a 2.0 build and sooner or later it will become impossible without breaking things as we will have real dependencies on 3.5. Right now the dependencies are very minimal but that will change. There is some new stuff in 3.5 for better handling time zones than what we are doing now, once we change to use that it will be very difficult to produce a 2.0 build. The only thing I'm really waiting for to use it is because its not yet working under Mono, but as soon as they have it implemented I want to use this new TimeZoneInfo class right away. And thats just one example. I also want to do more with the WCF RESTful web services toolkit, also want to be gin to implement some features in Silverlight.
3.5 .NET has been released for over a year, so my advice is update to 3.5 .NET SP1 and make your life easier to stay up to date with mojoPortal.
Best,
Joe