The main feature being touted currently a customisible browser for focused user groups is a concept called "Lanes" (screenshots here), which aim to reduce browser window clutter and "pop-up mess". According to the Tablane site: "Lanes let you compare pages, prices or images on diverse sites within a single browser window. Lanes make really good use of widescreen laptops."
They also have an RSS feeds feature called "Collections", which seems similar to Firefox's Bookmarks feature. They have plans to use Microsoft's SSE extension in the near future.
The Tablane developers are targeting a specific niche. They have to really, in what is a very tough market - with a dominant competitor in the form of Microsoft's IE. According to a write-up in Web2.0 Ireland:
"Julian tells me that they intend to carve out a niche in this market by customising their browser for focused user groups (an eBay browser, for example). This tactic of aiming for the Long Tail of browser users could be a very smart move - as web services shift more and more towards customisation, why shouldn’t the browser?
So far Tablane has been self-funded by the developers, who currently see themselves as being in the ‘testbed’ phase of the project, and are actively seeking user feedback on the current beta version. A commercial release is planned for January, with versions optimised for major e-commerce sites to come during the following months."