Will Lion X be downloadable for everyone?
No, the update will not be free (though it is yet unclear what the price will be, possibilities ranging from $29 to $129), and will only be free for those who purchase computers within 2 weeks of the update coming out (this is usually the time window for the free upgrades that Apple offers) in the summer. If you've purchased your computer recently, sorry, but you'll have to pay for it.