This is in reply to several postings above:

REI doesn't have the Colorado yet according to their website:

* Sizes and colors marked with an asterisk(*) are currently out of stock, but can be backordered.

Talked to Garmin Rep this week, still not slated to be available until Feb.

The Colorado has 96,000 pixels as opposed to the Edge's 38,720 pixels.
Does not include the virtual partner features the Edge has. You can load street maps also on either unit.
The Edge would be preferred as a training device, but as a multi-purpose unit, the Colorado is better.
The 400t includes topo loaded for the US and a shaded relief basemap of the world.
It allows for 3D terrain views on the unit.

The Colorado has a high sensitivity receiver, the Vista with it's high sensitivity receiver has an 18 hour battery life rating.
(Not much difference, especially considering it's processing load.)
They can use rechargeable batteries, so it's not that much of an issue anyway.

Unless you are competing in a race, the size/weight of the unit within reason should be fairly immaterial.
Larger screen is far superior for use while riding. The Colorado also replaces the features of the cycle computer if you have the speed/cadence sensor.

There are handlebar mounts for the unit, am hoping Ram-Mount will have their version shortly as I
have a 400t on order from Garmin.

As to saying it's obsolete is ludicrous.
The devices mentioned don't have the screen-size, waterproofness, durability etc. of the GPS.
Haven't seen the screens on the phones mentioned, but haven't seen one yet you could read in sunlight on a bar.
I wouldn't think of mounting my GPS equipped cell phone on my mountain bike.
Too small, too fragile, not waterproof, won't mark spots, trails etc.
Silly cell phone can't even handle having a button pressed while playing music - cuts out.