Here is question to notch about recent problems:
@notch Is the "Took too long to log in" message related to the web servers being overloaded?
And here is notch's response:
@iMineServer yes

So it seems as if the servers are being overloaded. They must still be migrating the servers over to their new housing. They stopped last night according to this:
We weren't able to finish the migration today, so we're taking a pause to sleep.
Anyways, hope this helps.