The Shimano internally shifting hub is called the Nexus. It's only 7 speed and Ty was right about saying it's not meant for high level riding. It's really only meant for cruising around town.
However... there's a variation of the hub that you GOTTA try if you get the chance. It's called "Nexus - Auto D". It's an electronic auto shift drivetrain. That's right! Bikes with auto tranmission!
Manly Cycles had one in stock... it was a Bianchi I think... called the Cafe Racer. I took it for a spin around the block... Wotta hoot! It actually works really nicely (for casually riding around the streets). And it comes in three modes... manual, auto and auto "sport" mode! Yowza! My wife would LOVE it! Too bad it cost more than $2000.
I should really start saving for my Rohloff hub... Maybe $100 a month til I've got enough? What a dream system... A freeride hardtail, with horizontal dropouts, and a totally closed drivetrain. Those hubs are BOMBPROOF from what I heard... And their gear range is pretty much the same you'd get from a 27 speed system.
Also, check out
http://www.nicolai.net for some AMAZING FS frames that use the Rohloff hub. If I could get two dream bikes... I'd probably get the Nucleon ST world cup frame built up. That is an insane bike.