There's no official information by Microsoft about the next version of WSS 3.0 / MOSS 2007 technologies. Nevertheless, there are bits of information that start to trickle down so that you can speculate about the most probable changes and improvements in the next SharePoint version. This version is likely to be named SharePoint 2009 or SharePoint 2010 and to be released just about when Office "14" is to be released, between 2009 and 2010.
My "educated guess" about the changes we can expect is:
- Native AJAX and Silverlight support
- More offline capabilities
- Microsoft Office files HTML viewers (following the line of OWA and EWA)
- Bi-directional BDC
- Native support for SQL Server tables as SharePoint lists
- Publishing module rewritten, to change the faulty Export / Import process
- More Business Intelligence capabilities for MOSS, as PerformancePoint 2007 matures
- Social networking improvements, maybe with Knowledge Management module included out-of-the-box
There are rumours that the first CTP should appear in 2008. So, all we need is just a little patience...
Disclaimer: although it should be obvious, the information in this post is based completely on my knowledge of SharePoint and the information I could find on the Internet.