Whitey - 8:36 am on Dec 6, 2010 (gmt 0)
WMT sitemaps plus a good heirarchy might be a good start as noted above. Pushing sitewide links into a 25 million page website to achieve a good spread of link juice would seem to me a bit of a tall order , even for Microsoft with a PR 9 or 10 home page.
Best to reserve this strategy for fewer areas of important emphasis. Mega sites with strong brand names probably have it easy for PR0 pages.
The thing that strikes me is the principles are the same for small and mega websites. What's different here is the magnitude of persons, departments and procedures that find it difficult to come together. and the longer it goes for the harder it becomes to alter the legacy build up - even for Microsoft - I'd say. So it needs to be done right at the very start of the web build process. digging one's way out is no fun.