The main difference is the "three years" between SharePoint 2007 (WSS 3.0) and SharePoint 2010. Microsoft didn't do nothing for three years.
The wiki is far better, with more of a WSYIWYG editing experience. This experience extends across all page editing situations. It also allows you to embed list items from other lists into a wiki page.
Overall, the experience is much nicer, through good use of a ribbon interface. SharePoint has always had a lot of capability, but it could be too much all at once. With the use of the ribbon, sets of functionality are presented together, and are hidden if you don't want to think about them.
Note that these are simply differences between the SharePoint releases, and have nothing to do with how TFS uses the portals. But you need to keep in mind that the portal functionality is based on the SharePoint platform, so the benefit is multiplied.