The new face looks to have higher resolution than that of normal human female player characters and could be indicative of the new graphics to come with the Cataclysm (e.g., this matches the higher resolution Worgen and Goblin masks that were unveiled some time ago). This leaves a few more bosses, most notably Thrall -- who's still wearing Level 30 greens -- to get the makeover treatment. We know that Baine Bloodhoof is replacing Cairne, so the latter probably won't be getting a new model. It's interesting to see who else gets a nice makeover. The higher resolution, multi-angled sweet stuff after the jump.
UPDATE: Zarhym says that the update to Jaina comes at a perfect time as she and Sylvanas Windrunner (updated for Wrath of the Lich King) would play key roles in Icecrown. He also reveals that "other heroes" or key figures in Warcraft lore will probably get the same upgraded graphics to give them a more distinctive look.
Patch 3.3 is the last major patch of Wrath of the Lich King. With the new Icecrown Citadel 5-man dungeons and 10/25-man raid arriving soon, patch 3.3 will deal the final blow to the Arthas. WoW.com's Guide to Patch 3.3 will keep you updated with all the latest patch news.