Not only have they been down, but even when they are up they are sending out Payment Confirmations up to 48 hours after the payments have actually been made! I have customers complaining that they paid two days ago, and I still haven't recieved confirmation. It's pandemonium!
There has been a PayPal outage recently - it was an absolute nightmare!
Surely for a website with several billion (it is owned by the owners of eBay - it's not just a coincidence that they recommend it) problems like this should be kept to a minimum!