Articles on Discovery lists a number of categorized resources about discovery services. Categories include:
- Presentations by vendors
- Library experiences, evaluations & case studies
- Misc comments on other issues
- Wikis/rough notes
- Webcasts (not free)
This great resource page includes more than fifty links to articles on the subject.
I highly recommend that libraries interested in discovery services give extra attention to the articles in the debates and library experiences sections so that they can learn about the technology with their eyes wide open.
You can access my writings about discovery services here.