Quoting from http://dsbl.org/faq:
- list.dsbl.org single-stage relays tested by trusted testers
- multihop.dsbl.org the outputs of multihop relays, tested by trusted testers
- unconfirmed.dsbl.org everything else, including tests done by anonymous testers; people could potentially sign up their own ISP’s mail server to this list
After that it says the following:
Note that the multihop and unconfirmed lists are very aggressive and have the potential for a high level of false positives.
GNOME uses list.dsbl.org among others. Gmail is only listed by unconfirmed and multihop.