Francois, I think the new PX series films will fit both types of cameras. This from the press conference (via @jesshibb on Twitter)
"Cassettes designed to fit any camera. No need to remove plastic nubs like current 600 film when used with sx-70 cameras."
Also,
Urban, you are aware that you could have started in with using instant film before this annoucment from TIP, right? Fuji still make several instant films some of which fit old Polaroid Land Cameras like the one I and many other Filmwasters use. The other films they make are compatible with their own Instax range of cameras.
While the Impossible Project's endeavours are spectacularly impressive it's not true to say that they have saved instant photography (or even analogue photography as I read today from one hysterical Twitterer who has obviously been swept along on a wave of excitement re this announcement
). Instant photography has been alive and kicking (albeit with less force) since the demise of Polaroid.
Now, before we go further you have to understand that the world of instant photography is pretty confusing; there are many formats, cameras, film backs, film types and whatnot. It's a bit of a world unto itself. Take some time to read up about it here
http://en.wikipedia.org/wiki/Instant_film before going further, but then feel free to ask any questions you want. There are lots of instant film fanatics here on Filmwasters and we're always happy to help.
To answer your specific question though, TIP's new film will satisfy instant film demand for owners of cameras like the SX-70 and the 'One' series (see
http://www.rwhirled.com/landlist/landdcam-600.htm for a full list). They will be very excited by today's announcement.