Herbert left a comment on my note below about the Open WorldCat URL syntax, and there were a couple of comments along similar lines on Karen's FreeRangeLibrarian post. The gist was why not use the OpenURL syntax for these links.
Sure .. we see OpenURL as very important moving forward (as discussed before) and it has always been under active consideration by colleagues developing Open WorldCat. We plan to provide a simple OpenURL resolver inferface to Open WorldCat in due course. Actual release time has yet to be established.
In summary. The current syntax is simple, human-readable, and human-constructable. We will complement it with OpenURL-based access which will allow additional service possibilities.