Looked at SharePoint a while back
nothing much to it other than the wide open ability to share directories and files. First problem is that setting up the access control is a major pain. Second problem is that it's fairly flexible (read unstructured). Biggest hassle with it, though, is that its mostly an internal organizational tool. Whereas Sarbanes-Oxley requires coordination between multiple entities (including the accountants/auditers).
Well MS has enuf money, I'm sure they'll make a play. They kicked our tires a while back, but I wasn't willing to integrate with .net or sharepoint. Time will tell.