Autodesk has announced that their 2010 products will be released on March 24, 2009. I found this post by Randy McSwain to be a good overview of the new features in AutoCAD 2010.
As of March 13, 2009, Autodesk no longer supports or offers upgrades from their 2006 products.
Because of the retirement of Land Desktop, I see that Autodesk is offering to crossgrade existing Land Desktop customers to Map or Civil 3D with special pricing. Subscription will probably be mandatory, but I’m not certain.