Yes, 360 included.
The news comes from Valve, who recently confirmed that the mod tools for Portal 2 - which have to remain PC-only due to "Windows dependencies" - will allow users to create content that will then be distributed across all platforms that Portal 2 will be available on. That's the PC, PS3 and the Xbox 360.
Also in the news is that Portal 2 will have two different ending sequences. However, they will be "reasonably obtainable" because, according to Chet Faliszek, "people would only watch the endings on YouTube", and that's something he hates.
[Via True Achievements]
