No, it's not just you. Xbox Live is down for everybody, but Microsoft is working feverishly to have service restored before the riots begin.
Attempts to log in to Xbox Live this morning are meeting with failure across the board. A quick network test revealed that my network is working flawlessly... Xbox Live, not so much.
Xbox Live is experiencing a temporary service interruption. We are aware of the problem and are working to resolve it as quickly as possible. In the meantime, we apologise for this interruption and thank you for your patience.
In the meantime, why not get reacquainted with morning television? It almost beats banging your head against a wall intoning "Why?" over and over again.
UPDATE: And just like that, it returns. No need to resort to savagery and cannibalism!