X1 are best known for their desktop search tool, but they offer an enterprise-wide solution that tries to integrate a lot of different data sources to allow searches that cover all of a company’s information. It mostly sounds very similar to Google’s search appliance, but they do have an interesting architecture that includes an Exchange component. It uses server-side MAPI, which limits it to Exchange 2003 and earlier unless you download the optional MAPI components for 2007. There’s also no mention of hooking into the event model, so I would be curious to know how much of a lag there is between a message arriving, and it being indexed. For my email search I’m working on Exchange Web Services support, since that’s the supported 2007 API to replace MAPI, and trying to get real-time access to the data by hooking into the Exchange event model.
It sounds as if they’re focusing more on the enterprise side of the world, after a recent change of management and a switch to a paid model for their desktop client. Back in November they mentioned signing up 60 large companies as customers for their enterprise service, which sounds promising, especially alongside their 40,000 desktop downloads at $50 each.