FYI: there are no feature differences between dnn3 and dnn4, in fact the code bases are nearly identical - except for some small changes necessary for it to work, as well as some use of generic's instead of arraylists to optimise the portal.

As for when DNN will move to asp.net 2.0, that's not a fixed date. It's a large overhead keeping 2 codebases in sync, as well as the additional testing required, so at some point future releases will be 2.0 only (just like the asp.net 1.0/1.1 switchover happened). A couple of factors come into this including how quickly the community move to 2.0, as well as how many hosts provide it. This question was asked in the November newsletter, and the results (as seen in the December newsletter) indicated that between 55-70% of people planned to move by now. The other factor is the IDE, and seeing as visual webdeveloper is free, this isn't the limiting factor that vs.net 2002/2003 was. I don't want to give any sort of estimate for when this will happen (as that would be a just a personal guess), as guess's often come back to haunt you, but you can probably look at the detail I've outlined above and make your own judgement.

Cathal

Unless you are modifying the core, there's no reason you can't do both.  I would recommend running DNN 4 as your code base.  Then, if you want to write custom modules, you can do that with VS2003 and compile against the DNN3 dll.  There are some differences in how you do things in VS2003 and VS2005, but most DNN3 modules run fine in DNN4.  If you can upgrade your development environment at a later date and not have to worry about upgrading your core, you will save yourself A LOT of stress.

Lessons learned from personal experience...

If you use 3rd party components, like Telerik RAD Controls, you should be aware they have a .NET1 and .NET2 version.  If you use VS2003 to build modules and use a control (say RAD Grid) with the .NET1 version and try it install it in DNN4, it will work fine so long as you have the correct radgrid.dll in your bin directory.  The problem comes in when you have some modules using .NET1 and others using .NET2 versions of the same control.  When you do that, you will get an error stating something like radgrid.dll is ambiguous, meaning it's confused by two versions of the same control living in your bin directory.  My advice is either use generic controls, like the regular datagrid, or be prepared to upgrade those modules when you make the switch to VS2005.  In most cases, upgrading the module is pretty easy.  For me, it was as simple as replacing the references and tweaking a few things.  Your experience may vary but as long as you know ahead of time, you'll be prepared when the time comes.