I'm just starting up in London. I only know one startup here, but that's just because I haven't bothered to look yet. My guess is that in Europe, London is one of the big startup hubs. Last.fm was based here. Cambridge also has a decent startup scene. HN user pclark's startup www.broadersheet.com is based there.

Personally I think London's an awesome city to live in. Given it's not Silicon Valley, but it's a vibrant exciting city. I love working here. I'm not looking for funding but from what I hear there's a ton of venture capital too here.

Drop me a line if you come to London.