In previous AutoCAD versions, if you wanted to create a table that was linked to a spreadsheet, you had to either use an OLE link or use a 3rd party tool. New to 2008 is a "Data Link" feature. This almost certainly replaces OLE linked objects, and may or may not replace 3rd party tools.
Another new feature to AutoCAD 2008 is the ability to perform an inverted xclip. Inverted clip meaning that the data "inside" the area you select is clipped out as compared to an ordinary XCLIP where the data "outside" the selected area is clipped. Microstation has had this for a while, so it's good to see it finally added to AutoCAD. Read more about AutoCAD 2008 Xclip
Starting with 2008, there is no "Deployment Wizard" any longer, at least as a separate application that you have to install. So how do you build the deployment if there is no deployment wizard? You'll see not long after you insert the DVD into the drive.
If you are planning on upgrading to AutoCAD 2008 32-bit, and you have existing LISP, VBA, or ARX programs, will they work? Generally speaking, yes. You may have to make a minor adjustment to your code, but for the most part there shouldn't be any problems.
Have you ever set a system variable and then you are working along and that sysvar is changed to a different value? Many people will ask how or why it "changed itself", which obviously it can't do. Of course what is really going on is a program, whether it be an internally defined command, or a lisp/VBA/ARX routine, has changed it. Read more about System Variables changing on their own?