There's an interview with Valve guru Doug Lombardi posted over at FiringSquad that talks more about Episode 2, Team Fortress 2, & Portal. Ep1, Ep2, & TF2 will be released all together as a full expansion pack next year. I personally am really looking forward to TF2.

"FiringSquad: The newly revealed Team Fortress 2 is a lot different than the game that was first shown at E3 in 1999. What caused the change in art style to a cartoony 1960's spy look? Doug Lombardi: Starting with the characters in TF2 we had a set of goals that we wanted to accomplish, ranging from making sure that you could identify a class and its abilities from just it silhouette, to allowing gamers to form an emotional attachment to the class they most liked to play."