According to an article over on theregister Internet Explorer 7 is on the horizon.

Details of Microsoft's Internet Explorer 7.0 are starting to emerge, and if the rumours are true, IE 7.0 will have tabbed browsing, a built-in news-aggregator, and could be integrated with Microsoft's currently-in-beta anti-spyware product

Well I am struggling to keep up with the speed of Microsofts releases as it is, 2 years since the last new browser wasnt it, or maybe it could be even longer.