Has there been any information released regarding what features are included in SharePoint Foundation and what features you need SharePoint Server to use in the 2010 version? I can't seem to find anything related to that.
The Services in SharePoint 2010 Products poster has a table detailing the services available in Foundation and Server so this may be worth a look: http://go.microsoft.com/fwlink/?LinkID=167090
Basically, BCS, Usage & Health Data and Subscription Services are available in Foundation, all others are available in Server Std or Enterprise.
Probably worth noting that the managed metadata service is not available in Foundation which is proving to be a pain.
This edition comparison page on Microsoft's site is an excellent resource. It allows you to filter by feature area, too, which is useful.
Typically of Microsoft, the "killer app" many people desire is in an expensive version. I know there must be skillions of users who want Word Automation Services simply for rendering purposes who will have to invest in heaps of unneeded features in order to get this functionality, which could have just as easily been a .NET 4.0 library.
It's just like Ultimate being the only version of Windows that allows you to change the UI language, so multilingual families like mine have to shell out big for this one feature.
The editions comparison and the service applications visio diagram are both great references.
I also recommend the Feature Comparison Table in Getting Started with Enterprise Search in SharePoint 2010 Products.
Doing research for a book I contributed to, I found that I would recommned installing Search Server Express over SharePoint Foundation in many cases. It has a similar licensing approach and includes SharePoint Foundation, but provides many features otherwise only included in SharePoint Server.
And the benefits, don't stop at Search features. For example, the Secure Store Service is installed with Search Server Express, but not with SharePoint Foundation. This is very useful in combination with the Business Connectivity Services which are included in SharePoint Foundation and through Foundation's inclusion in Search Server Express.