Twitter has added a new feature which "brightens up" the appearance of your Twitter profile. It is a large graphic that you can upload similar to Facebook's Cover Page. This graphic is large in size, 1252 pixels wide by 626 pixels tall with a max filesize of 5Mb. Twitter's new layout puts your existing Profile Photo smack in the middle of the new Header Image. See this example of mine...
You do not have to use a photo of yourself, some choose to use a company symbol or logo as their Profile picture. This new feature makes a Twitter business page more professional and attractive to potential followers. You can embed a phone number, website or blog or any other info you'd like in your Header Image graphic. Also popular and still available for your customization is the Background image. This is a smaller file, 800Kb that can be used behind your Twitter feed. Some choose to tile the image, or you have the option of leaving it as a single image and LEFT, RIGHT or CENTER justifying it. A teeny bit of creativity allows you to get a nice complimentary message across to viewers of your Twitter Profile through the use of the Background Image graphic. See this example from cNet below...
Some niceties from the team at Twitter... wouldn't you agree?