Don't know much about them at this point, but saw a commercial on TV last night. They're starting up 1 July, flying between BCN, BRU, and PAR.
I just priced BCN-PAR nonstop for 10€ each way.
A bit more from a news story I dug up. They´re flying brand-new A320s, and are partially-owned by JetBlue.
http://www.vueling.com/