Looks like the Asian PlayStation website has spilled some beans. On December 18, the Hong Kong PSN will be getting not only a Solid Snake Sackboy, but a character and level pack as well.
No prices are listed, but the items themselves most certainly are. There are individual sackboy costumes for Solid Snake, Meryl, Screaming Mantis and Raiden, a pack selling all four of those, and a "Level Pack", which looks like it includes stuff like creepy, over-sized manscenery.
There's of course no mention of this on any other PlayStation website - including the notoriously leaky Japanese one - so there's no guarantee these will appear globally once Thursday rolls around. But every other LBP update has gone live globally, so keep your Kojima-caressing fingers crossed.