The B9 Tribeca is powered by a H6 boxer engine making 256 horsepower. This engine so far has only been paired with a 5 speed automatic transmission.
Like all Subarus since the late 1990's, the B9 Tribeca is only sold with all wheel drive. This is a feature that Subaru owners take pride in, as the symetrical all wheel drive system tends to work better than the AWD systems that are tacked on to otherwise two-wheel drive cars by other companies.
Some significant changes were made to the 2007 B9 Tribeca in response to some consumer complaints. The design was tinkered with, along with the suspension and luxury features.
XM Satellite and iPod connectors come pre-wired in the Tribeca, and a navigation system can be upgraded with a rear camera that is part of a parking assist system. A Special Edition Tribeca gets a new mesh grille, better wheels, and an XM radio.
It might be a little to early to look for a Subaru B9 Tribeca on the used car market. These cars have excellent crash test ratings, so they'll be a fine choice when they do start popping up on the market in greater numbers. The one place you can look is eBay auctions, where some dealers dump leftover stock.