Here's an excerpt from the IGN article that describes the new expansion:
Expanding on the original Spore game, the Spore Galactic Adventures expansion pack gets your creature out of its spaceship and exploring colorful and wacky new planets. Players can turn their creatures into space captains, battle epic monsters in intergalactic arenas and engage in intense planet-side races. In each mission, players earn experience to rank up their captain and earn game-changing items such as the Plasma Pulser and Swarm Magnet. In addition to the adventures in the box, players can download 10 all-new adventures created by the writers of the outrageously funny, pop-culture parody TV show, Robot Chicken.
And from the Spore Galactic Adventures website:
Get out of your starship and turn your Spore creatures into legendary Space Captains. For the first time, beam down with your allies to take on action-packed, planetside adventures. Complete quests, collect rewards, and even create and share your own missions. [...] PLAY a variety of Maxis-created missions as you explore planets all over the galaxy! LEVEL UP your Space Captain and earn more than 30 powerful new accessories! CREATE your own missions with the all-new Adventure Creator, then share them online!
You can check out some of the "adventures" over at the game's official Sporepedia, and/or follow all the latest Spore-related developments through the game's community Youtube channel and Twitter account.
Two things that interest me in particular about this (apart from the obvious UGC angle) are: 1) my staple question of whether kids are getting involved in the content creation (they sure do seem to like Spore), and 2) how does the Adventure Creator editor compare with Microsoft's Kodu?