I think Microsoft has resisted supporting tabs in their browser because it acknowledges the deficiencies of using windows for the same functionality, thus undercutting the desktop metaphor.
I expect Avalon to end up being primarily used as infrastructure for MS's future browser based platform, similar to how XUL will be used by Mozilla.
RE: IE7 on the way with something called "standards" in mind
I think Microsoft has resisted supporting tabs in their browser because it acknowledges the deficiencies of using windows for the same functionality, thus undercutting the desktop metaphor.
I expect Avalon to end up being primarily used as infrastructure for MS's future browser based platform, similar to how XUL will be used by Mozilla.