You can tell just by looking at this guy how excited he is about mashups. Energy and excitement just rolls off his picture in waves.
Really, Tim's a great guy, and spoke to India's Express Computer about business mashups. The gist is that organizations have too many portals and too many applications that suck up too much of IT's operating budget.
The benefits of aggregation into a portal are lost if end-users then have to remember URLs and passwords for multiple portals. Mashups in a portal context allows users to aggregate aggregations so they don't have to jump around from portal to portal.
The effects of too many applications are twofold. First, just as with portals, end-users have to jump from application to application to get anything done. The second is that there is no budget to work on new and innovative applications because IT's budget is already being spent maintaining existing apps. Mashups help with application aggregation, and because they can be developed without writing code, tech-savvy end users can build these apps themselves.
The article doesn't offer a lot of new and deeply technical information, but it does summarize nicely the view of mashups by vendors such as Serena Software and Oracle, as well as Gartner's Dave Gootzit. At the risk of being tagged as a member of the lazysphere, I'm just going to point you at the article rather than commenting on it.