It's a good bet that 2007 will be known as the year of the square-headed driver. Nike's SasQuatch Sumo2 (for Super Moment of Inertia) is the first one to reach the market. (Similar designs from Callaway and others are hot on its heels.)
Nike blends a titanium body and composite crown to create the odd-looking head. The key to the square head is that weight gets placed in extreme heel and toe positions that don't exist in more traditional designs. Moving mass farther to the perimeter produces a higher moment of inertia (or MOI) so the club won't twist as much on heel or toe contact.
Bottom line: You'll get straighter, more controlled drives. Another new SasQuatch, the all-titanium Sumo, is built on a similar chassis. The Sumo also has a high moment of inertia, making it only marginally less forgiving than Mister Square.
Sumo2: $479 (graphite)
Sumo: $359 (graphite)