I've had a few posts about Discovery Services piling up in Google Reader:
- Library Technology Reports, Volume 47, Number 1 / January 2011, is an issue dedicated to Web Scale Discovery Systems.
"This report describes in detail the content, interface, and functionality of web scale discovery services developed by four major library vendors: OCLC, Serials Solutions, Ebsco, and Ex Libris." (LTR is available in Academic Search Complete and Academic OneFile). - Marshall Breeding has a brief column in the latest issue of Smart Libraries Newsletter entitled Building Comprehensive Resource Discovery Platforms.
"When populating an index for a discovery service, it’s helpful to gain access to large numbers of articles in a single package through a deal with an aggregator. It’s also possible to represent the same content in the indexes through cooperative arrangements with the primary publishers and content providers covered within any given aggregated database of article content." - As part of a larger post called Finding your way around federated search, Sol Lederman includes links to 4 articles from his Federated Search Blog that discuss Discovery Services.
- Finally, on the Library Journal website, Judy Luther & Maureen C. Kelly write about The Next Generation of Discovery.
"When content is abundant, finding the right content becomes the challenge."
If you can only grab one of these, I think I'll recommend the last one. A very good overview and lots of things to consider when evaluating a Discovery Service.