I noticed this a few weeks ago when I purchased a 2012 Uberti. The lines are different from the 2006 Uberti I used to own.
1. The grip shape and angle are different. The 2007 (and newer) guns have more room behind the trigger guard, and the grip angles backward just a tad.
2. The frame is a bit taller (in the vertical direction) on the revised 2007 model. This is because the cylinder window is larger to accommodate Uberti's .45 Colt conversion cylinder. This makes the stepdown from the frame to the barrel, a bit sharper.
3. More barrel threads are visible on the revised 2007 model.
4. The 2007's frame is forged. The older frames are castings.
These changes coincide with the introduction of Uberti's 1858 cartridge conversion.