Just announced from Jens Bergensten twitter account announced Minecraft will support name changing in the near future but not before 1.8 is updated! Note this will also require you to migrate to a Mojan account if you have’t done so already.
As far as Xbox and PS3 its in the works, but no eta as of know.
In other news Minecraft PC 1.7.6 will be out in March, but 1.8.0 unknown (best guess: May). MC:PE 0.9.0 also unkown (best guess: May)
One of many FAQs: Name changing in the PC version *will* be supported, but not before 1.8 and an update of our web services
— Jens Bergensten (@jeb_) March 5, 2014