I took the opportunity to ask the SQLCAT guys at this year's SQLPASS about an issue with storage hangs I had been testing a couple of weeks ago. In testing our SharePoint 2010 infrastructure, I ran into one scenario in which SQL server loses access to its underlying disks. The mirror eventually takes over, but SharePoint does not recover until either the storage comes back online, or the primary is completely offline.
Since it was hard to say whether the issue is SQL Server, SharePoint, or the .NET provider, I talked to pretty much everyone. While there isn't a definitive answer, it's an easy scenario to reproduce, so the webapps team said they would test it with the new "Always On" in the new version.
For the moment, I'm documenting it as a known issue requiring manual intervention to bring SharePoint back online.