Lion is ready! No doubts about it!
If Steve Jobs has anything to say about it, it might be "We have a great team here at Apple, but they don't sit on their asses every-time we're successful."
Apple works hard and they anticipate release dates... Most importantly work on Lion started right after Snow Leopard... They released Snow Leopard, had fun for a weekend, and went back to work on Monday.
Also Apple is pretty confident about this date, sources say. They also like to leave the rest of the world off with some goodies... Why not Mac OS X.
I can see an iCloud delay due to licensing, because most other companies are in it for the money, not the passion...