You can get it from here:

http://prdownloads.sourceforge.net/guess/guess-20061026.zip?download

The most important stuff is:

New features:

- Prefuse now works
   -  If you run GUESS with the --prefuse option you should get a
prefuse front end, the little pop up lets you control the forcelayout
controller.  It doesn't quite support all the standard GUESS features
yet, but things like color, label, width, placement and centering work

- Cut and paste from console is better
  -  There's a menu item that lets you copy and paste to/from the
console and makes use of the system clipboard so you can do so between
applications.

- GDFReader to load in GDF files later
  - new support to load up GDF files

- Can load in files after the fact
  - there's a new menu option to let you load up gdf/xml/pajek files

- Can draw on "drawing" layer
  - you can now draw in the top layer and add visual annotations
programmatically.  It's a little bit of an abstraction violation, but
it seems to do the trick.  Manual updates on this coming soon, but
there's a discussion on the GUESS-discuss list about this.

Minor changes:
- changes to default colors
- strokecolor now sets the color around a node
- minor tweak to touchgraph interface