Title explains it all. Apparently its up on a few other EU PSN territories too... except the Dutch, no Batman for you. You may see an ad for it, but it will lead you else where, just go to search and type in "Batman" it should be the third or fourth result you get. Demo is about 1.4GB, and I'm in the process of downloading it.
Not sure if its on EU 360s or not, but if you don't have a UK/EU PSN account, they're really easy to make, that's what I did.
Regardless, the demo shall be up everywhere officially tomorrow.