Looks like Trek has gotten around to updating their website with the 2010 FX lineup. I've already seen some at the LBS and they look sharp. I'm glad I picked up an '09 7.6 and the many miles I've logged this summer have been great on it. That said though, I'll probably pick a '10 model up for my wife as an update to the old Schwinn MTB she's been riding around on.
Overall, pretty solid updates. the SSR wheels are redesigned, 7.2 gets the nice Alpha Black frame, small increases in price on some, but some nice small decreases on the higher bikes. 2009 prices listed in parentheses for comparison. I like the white 7.7 the best, followed by the Darth-Vader-esque 7.5.
7.1
$439.99 ($439.99)
Alpha White Aluminum
Shimano M191 FD
Shimano Acera RD
Bontrager/Matrix 750 Wheels
Steel Fork
7.2
$529.99 ($489.99)
Alpha Black Aluminum
Shimano M191 FD
Shimano Alivio RD
Bontrager/Matrix 750 Wheels
Steel Fork
7.3
$639.99 ($639.99)
Alpha Black Aluminum
Shimano C102 FD
Shimano Deore RD
Bontrager Nebula Wheels
Steel Fork
7.5
$919.99 ($899.99)
Alpha Black Aluminum
Shimano Deore FD
Shimano Deore LX RD
Bontrager SSR Wheels
Carbon Fork
7.6
$1209.99 ($1259.99)
Alpha Black Aluminum
Shimano Deore FD
Shimano Tiagra RD
Bontrager SSR Wheels
Carbon Fork
7.7
$1869.99 ($1979.99)
Alpha Black Aluminum
Shimano 6703 FD
Shimano 105 RD
Bontrager Race Wheels
Carbon Fork
7.9
$2619.99 ($2749.99)
Trek TCT Carbon
Shimano Ultegra FD
Shimano Ultegra RD
Bontrager Race Wheels
Carbon Fork