The t4i also has an upgraded processor (better low light performance) and shoots 5fps stills. Also has a touchscreen.
-Just a note about the digic 5 (t4i) processor vs the digic 4 (older one)
"The new Digic 5 processor is 6X faster and creates 75% less noise than the Digic 4 processor"
Keep in mind that the digic 5 is the first Digic generation to be designed from the ground up for dealing with HD video and stills processing in the same camera