Putting Express on it is such a huge marketing gaffe that one day it'll be taught in marketing classes.
I can just see those cheesy press releases... "with large overhead bins, and a lavatory and flight attendant for added comfort".... who cares, usairways.com will still say "operated by US Airways Express, Mid Atlantic Airways"... thats when the customer will move on to see what the competition is offering.
In a customers mind Express is Express. The regional jet has gone from a welcome novelty on turboprop routes to a loathed experience on mid-haul routes that most will suffer through only once.
From a logical standpoint, there is no reason for them to not just call it US Airways. Technically, it is operated by employees on the US Airways seniority list, and is a "division" of the company. Although single class, the product is closer to an Airbus than it is to a Beechcraft or Dash 8, and in some ways superior. The aircraft has a range of 2000 or so miles and will serve markets that warrant other airlines mainline equiptment. As routes are added, you will see longer and longer routes, mosstly 737 routes.
Initially thay were to be under the main brand, and have a premium cabin. Mr. Siegel made quite a big deal about this when he toured the bases promising jobs for all and profitability nearly two years ago. Now that he's seen the willingness to sell out the more junior employees to save a precious few senior ones, things have changed. Why not put them at affiliates (where it would have to say Express on it)? The 190 is right around the corner, and that finally eliminates the need for that pesky "mainline" US Airways, clearing the way for his dream of an alliance of jaw-droppingly low-cost airlines flying as "US Airways". Anything international or transcon (which isnt much) can be flown by United Airlines, which has experience being a real airline.
Betcha they'll paint over the Express then. <_<