I found this powerpoint presentation
by Bob Hansen of Briess Malts. It's from a presentation he gave at the National Homebrew Convention, with tips for mashing and sparging high gravity beers. A little hard to follow without the presentation audio, but there's lots of interesting charts and details that I didn't personally know about.
Oh, and I found the link via Basic Brewing Radio
which is my new favorite podcast. This week the host interviews Hansen about this topic... haven't listened to the episode yet but I imagine it will have lots of good information.