It appears the release date is actually the 27th rather than the 24th. This is from a post from Sony Mobile US on Facebook.
They're having a special event at a Best Buy in NY beginning at 1 minute past midnight on the 27th where they're giving away signed copies of a CD by Maroon 5 with the purchase of an Ion by the first 50 customers.
Only a 3 day difference, but it sure would be nice if they gave a firm date that wasn't so round-about.
If you're getting it just becuase it's playstation certified, don't do it man. Get a Vita. I don't know if you've ever actuially held a vita in your hands but oh damn, it feels better than any phone i've ever owned.