Several CAD packages work with SharePoint, a piece of Microsoft software that searches through data. Solid Edge has been a big proponent of it, and more recently Inventor noted that it will be getting onto that particular bandwagon.
The problem for the CAD user is that SharePoint isn't free. But soon a stripped-down version will be. Search Server 2008 Express returns search results from multiple databases, local computers, and Microsoft's sad Live.com Internet presence. The free version is limited to running on a single server; the non-free one allows the software to run on multiple server. In beta soon, shipping by June of next year, requires Windows Server OS, which isn't free.
If you can't wait until next year, IBM and Google already have their free enterprise search software products on the market. Dunno if they work with CAD software, tho.