The official Slackware packages for GNOME are getting really outdated. There have been rumors that GNOME will be dropped in the next release.
If you want GNOME 2.8, then I recommend trying out Dropline Gnome. It's an i686-optimized version made specifically for Slackware 10. I've been running it for about a month now, and haven't had any issues.
You can find it at
http://www.dropline.net/gnome/