According to this Game Reviews piece, Bethesda’s confirmed that the PS3 version of Fallout 3 won’t need a hard drive install.
“We do not do that, no. We do the put you know, put the stuff down there that we need to be there, we can stream it on in and out of there but we do not do the ‘we need ten minutes of your time,’” an unnamed spokesperson told the site.
“We will cache the same way on both (Xbox 360 and PS3) we basically just like everybody you know if you have a hard drive, it does this.”
More through the link. Thanks, James!