Capcom has outlined the changes coming to Super Street Fighter IV from the promised 2012 Edition patch. As expected, some tournament favorites like Akuma and Yun, have been tweaked to make them less devastating, though overall Capcom says it is "focusing on buffing up weaker characters, rather than nerfing existing ones."
The Capcom Europe blog gathers up translations on the Capcom Unity blog. Most of the classic characters like Ryu, Ken, Sagat, and Chun-Li are getting only minor changes to make them more user-friendly, while others like Blanka and Zangief are receiving general balance changes. Some characters like T. Hawk are just receiving changes to make up for the rest of the roster's alterations.
Most characters received minor buffs, but Gouken, Adan, and Hakan seem to be getting the lion's share of improvements. Akuma is receiving some light nerfing, particularly in move loops, and C. Viper and Seth are both receiving a bit of a downgrade as well. Yun, usually cited as the most overpowered character, is probably getting the most nerfs. Capcom says this is to make him less of a "scrubby character" and to focus his talents on "players with strong technical skills."
The announcements didn't outline specific release plans for the balancing patch, but it's planned for location testing in Japanese arcades soon.