Blizzard has released a preview of the Mage Tier 13 armor set that will be available in World of Warcraft Patch 4.3. You can click on the above image to view a larger version. Here's their description of the Timelord Regalia:
"It’s fun to put a spin on any caster class that moves it away from the usual wizardly archetype, and this set provided the perfect opportunity to do just that. Gnomish clockwork technology is an established part of the Warcraft universe, but it’s not something we’ve incorporated into a tier of player armor before. The combination of moving cogs, quilted fabric, and lots of buckled straps give the set an intriguing 'techno-mage' flavor."
In addition to the Tier 13 reveal, Blizzard has posted a visual guide to mage Tiers 1-12 for Transmogrification purposes. You can view the mage's armor history after the jump, and check out Wowhead's guide to find all your old tier gear. Also, be sure to browse through all of the currently released Tier 13 previews.