In principle there isn't any reason a YC partner couldn't just give a talk if they wanted to. For example Harj did a session at HackerNews London just over two years ago [1]. I don't recall it being an official 'YC Event', just one of the partners who happened to be in the UK at the time and was willing to do it.
However, looking at the current list of YC partners [2], I don't see many that might have ties to Europe, such that they'd be visiting much (never mind the imposition of giving up family/holiday time to give a 'work' talk).
However, looking at the current list of YC partners [2], I don't see many that might have ties to Europe, such that they'd be visiting much (never mind the imposition of giving up family/holiday time to give a 'work' talk).
[1] http://vimeo.com/30800728
[2] http://ycombinator.com/people.html