In my opinion it also depends what kind of subject you're using Wikipedia for.
Compare subjects involving history with subjects involving science. The scientific subjects are way more reliable than the history subjects. Basicly the sources for history can come from any kind of source. But the scientific information comes straight from multiple tests.
And what about summaries, what kind of source do they require, these kind of subjects on wikipedia are very not-reliable.
{off topic: How on earth do I change my nickname, admins don't seem to eager to help me}