Twitter are on a massive revamp, and as part of their new (coming soon) layout, they are also rolling out enhanced profile pages for brands. It is looking a little similar to Facebook's new 'Cover' photo. The header image will be 835 x 90 pixels.
There will also be a few new cool features to maximise your audience's engagement with your profile such as a (Free) Promoted Tweet; you will be able to highlight a tweet to the top of your timeline as the first thing viewers will read when they enter. This could be your latest product special, or important news etc.
The enhanced profiles are currently being selectively rolled out to a chosen few. Then will be rolled out to the public in the coming weeks to months.