Twitter is testing a massive redesign that looks like its focus is to challenge Facebook. The design being testing was spotted by Mashable's Matt Pentrozio. It features a grid of tweets rather than a list, a bio and photo area on the left and a number count for photos and videos, which makes them much more of a prominent feature. Now just because Twitter is testing this design doesn't mean it will launch. Twitter is known for testing things that have never made it to the public, but this at least shows they're trying very different things to entice users to the network.