We have an enterprise portal. The home page is customizable for each user. There are dozens of bricklets people can include. Our portal does not address user role based information at the business level.
Some business units have made portals of their own and collaboration system allows that kind of thing too. So, we have an embarrassment of riches in our portal explosion.
We spent the last 2 years struggling with this issue. Because of our various repositories, you had to search each repository in turn, and many you may not know exist. We started pulling together enterprise products from the vendors.
One additional note is that the mechanisms that work well on the internet don't scale down to even the large enterprise because, by comparison, the volume of content is microscopic. We have found some vendors that do have products that work right for the enterprise and that will go along way.