Well, they pay on acceptance. So I would guess it's not retroactive to anything already accepted, but I don't know.
Here's the breakdown of payment specifics from their Submissions Guidelines page:
Analog pays 7-9 cents per word for short stories up to 7,500 words, $525-675 for stories between 7,500 and 10,000 words, 7-7.5 cents per word for longer material, and 5 cents per word for serials. We prefer lengths between 2,000 and 7,000 words for shorts, 10,000-20,000 words for novelettes, and 40,000-80,000 for serials. Fact articles are paid for at the rate of 7 cents per word.
Checked Asimov's, too. They have also upped their rates to 7-9c/word for up to 7.5k. They pay 7-7.5c/word for longer work. (With a caveat about not paying less for a longer story than they would for a shorter one. I guess for things that are just a little more than 7.5k?)
Thanks, Aggy. Suddenly the long crickets from them are a plus for me...hope springs eternal...