Okay guys, here is a very short list of the good and bad things in SharePoint 2010 from my perspective as software architect. Let's get started...

The Good:

• Improved integration with VisualStudio 2010 that goes beyond the available features in VSeWSS.
• Support for LINQ and extended support for XSLT, which will - among other things - be used for list generation (although CAML will unfortunately stay an important part of the platform).
• Better AJAX support (and I don't mean the Ribbon UI, because CSS and JavaScript have nothing to do with AJAX).

The Bad:

• SharePoint 2010 will be based on .NET 3.5 and Windows Workflow Foundation 3.5 (instead of the rewritten version of 4.0). This is especially sad because I rejected WF 3.x from the very beginning and was very pleased to see Microsoft creating a complete rewrite.

Unknown:

• It is still unknown if Microsoft fixed the annoying performance and development issues with undisposed objects (see http://www.sharepointdevwiki.com/display/public/When+to+Dispose+SharePoint+objects for more details). This is one of the major architectural drawbacks of the platform and definitely something, Microsoft's engineers should fix as soon as possible.
  

I will update this post as more information become available.