WordPress Multi-User is the platform used by http://wordpress.com to host 6 million sites. All those separate sites, share a single database (OK, you split it at some point for performance reasons). There are plugins which also exploit the virtues of WordPressMU to offer greater user functionality for content discovery. RSS/Atom/RDF/JSON feeds are available (in combination if desired) from almost every data end point.
What if a WPMU platform hosted every UK HE library catalogue in multiple, individually branded Scriblio sites and exposes the data via Triplify as RDF and pushed it to Talis Commons for your pleasure?
Much of the work has been done. It just needs a few people to polish the components and show it working (University of Lincoln could host a proof of concept). Once your OPAC is in WordPress/Scriblio you benefit from one of the largest pools of open source developers (with over 4000 extensions), working on cutting edge web publishing.
This is a cool idea! When I first saw Scriblio mentioned on twitter in regards to this, I thought: great but why Scriblio and not something like VuFind or the many other next gen catalogues that have emerged in the last year or so. But the moment I read this is all made sense. Scriblio, Wordpress MU, RDF... a perfect combination.
I've always held a quiet belief that a 'union catalogue' is one of those things that has always eluded us, but is actually quite possible if you just sat all the tech geeks down in a room for a while (whether it be Scriblio, z39.50, SRU/MODS, VuFInd).
I'll try and have a look to see what format this wants our data in, and how easy it is to extract it in such a way from Talis.