yip!
http://www.viega.net/xchg/en-us/hs.xsl/4741.htm
Interesting theory with the faster hot water transmission, and individual lines to each appliance.
I've never given it much thought, but PEX tube is so cheap that the amount of money you save on T fittings will cover a significant portion of your extra tubing cost.
Take a typical cold supply for a bathroom:
25' of 1/2" PEX, 2 T fittings, 6 rings, and maybe 15' of runners VS. 3 30' lengths of 3/8 PEX
40' of 1/2" will run ya $10, and the fittings another $4-5 easily.
90' of 3/8" will run ya $20
Not a bad deal to get that isolation and fast hot water. Never getting scalded in the shower when someone hits the toilet is a bonus.
With all that said, what these guys are selling is an idea. They are not the cheapest valved distribution manifolds in town (but might be the nicest-looking)