At last year's New York Comic-Con Marvel announced that 20 of its February 2015 covers will have retro variants done by Phil Noto. Fifteen of them have been released randomly over the past year. You can see those below (and above).
Yet to be revealed at the time of this writing are the covers for Avengers, New Avengers, Deadpool, Legendary Star-Lord, and S.H.I.E.L.D.
The covers were inspired by a series of drawings Noto did back in 2011 that captured the glam parties thrown by the Marvel Superheroes back in the 50's and 60's. They are candid and Time Magazine style photos taken by the fictitious Hank Pym, the future Ant Man and photographer friend of choice for all Marvel heroes bashes. You can see some of that collection here.
In an interview with Phil O'Shea at NYCC in 2014, Noto talked about how the project all came about:
It all started when I began posting some retro-candid “photo” sketches on my blog featuring Marvel characters. I had been looking at some old photos of Hollywood stars from the 50’s and 60’s just hanging out and thought it would be fun to do a comic version of that. I started adding little anecdotal stories to them as told by Hank Pym, the supposed photographer. I don’t know why I chose him but I just thought he seemed like a good choice to be a shutterbug and would’ve been around a lot of these characters. I ended up calling the series the Hank Pym Photo Archives. They became popular on Tumblr and Jeanine Schaefer, my editor at the time, really dug them and wanted to do something more with them. We got very close to doing a retro series but it ended up becoming too complicated in terms of schedules, continuity, etc. So I just kept posting some on my blog from time to time.
Cut to earlier this year and I get a phone call from Jeanine with the brilliant idea of doing a series of covers in the same retro style. It was a no-brainer. I’d be able to do the various characters and not have to worry about any specific storyline or anything.