Here's the changelog for v.8, from the Sophos forums.

This release includes a number of new enhancements including:
Scheduled Scans: Now, in addition to On-Access and On-Demand Custom Scans, you can also create Scheduled Scans to run automatically on a pre-defined schedule
Live Protection: Gives you a direct connection to the very latest information we have about new Mac threats. Using our global intelligence network, we can identify new threats quickly and make sure your Mac is protected—immediately. Live Anti-Virus has been available in our Windows products for a while now and I'm really excited that our Mac customers will now be able to benefit.
Enhanced user-interface: We’ve improved the user-interface and made the product even easier to use

Since I upgraded to Lion, this software no longer works (PowerPC only). Blacktree, it would be great if you could update this little gem for Intel! I haven't been able to find any other recent software that's as simple as this. Auto-bpm detectors often give incorrect results, especially if the bpm changes during the song or if the song has many beat subdivisions or unusual time signatures (e.g. 6/8).

See here for the changelist: http://www.bergstrand.org/brian/software/ChangeDesktop/notes.html

This is the only desktop changing program that I have seen that has the set of features that I want: parse an entire directory tree for images, change images on a schedule (e.g. every five minutes for me), provide many options for display sizes of the images, limit the minimum size of images that will display (e.g. no images smaller than 1024x768), etc. It also has lots of other features, like transitions and display of the EXIF tags of images.

Unfortunately, it isn't updated very often and it has tended to have memory leaks that limit my ability to use it. I keep my computer on 24/7, but after a couple days of running CD its memory footprint bloats to the point that it slows down the rest of the computer (I have a Mac Pro with 6 GB of memory). The author stated that he fixed some memory leaks in 3.1, so hopefully that will take care of things.

One other thing that bugs me is a feature change that was made in the transition to v. 3.0. The author removed the ability to go directly to the currently displayed image in the Finder. The menu option “Now Showing -> [Image Name]” looks like it should take you there, but it instead shows a QuickLook-style window of the full image. Not very useful, in my opinion.