Twice now I've seen install.php come back from the dead. That is, a WP installation is up and running fine, but I see the initial install page that links to install.php instead of the blog. When it first happened to me I panicked, then opened the page in another window to discover my blog was there. I brushed it off as some weird browser cache problem, but I just saw it on someone else's blog. I was probably running 1.0.2 at the time; I don't know what he's running.
I understand that you can't break an install by running install again, but unsolicited offers to install the software are distressing nonetheless.