I have used the phrase search engine interoperability in these pages a couple of times. This is a play on search engine optimization, which some do not like (although I think we should not avoid using a standard industry term). We value interoperability in libraries, and I think that a large part of SEO is, effectively, interoperability with search engines, where, to repeat myself, interoperability means managing resources in ways which promote effective crawling, indexing and ranking by search engines.
In this context, I was very interested to read Andy Powell's critique of 'web usability' in an institutional repository. He looks at how a particular document is presented and how that 'plays' with search engines in a web environment. Andy suggests that his experience here is probably broadly representative of this class of service, something I am not in a position to judge. He examines a range of features and concludes in this way ...
OK, I apologise... I've lapsed into sarcasm for effect. But the fact remains that repository jump-off pages are potentially some of the most important Web pages exposed by universities (this is core research business after all) yet they are nearly always some of the worst examples of HTML to be found on the academic Web. I can draw no other conclusion than that the Web is seen as tangential in this space. [eFoundations: Repository usability]
Update: Andy has a followup entry looking at a document in another institutional repository, using a different technical platform.
Update 2: There is an interesting stream of comments on Andy's first post.