hmm. I'm trying to re-install from scratch now (deleted and recreated my database - now it has no tables), but as soon as I get to install-config.php?step=2 (which it says is OK, can talk to the database) , and then install.php, it says "It doesn't look like you've installed WP yet" and reloads install.php with the message "No input file specified." AGAIN!
I re-uploaded clean PHP files for everything, from the 1.0.2 dist. This is on Windows 2003 with latest PHP and MySQL. I've tried the thing from scratch and still get this, although previously I was able to get the latest alpha running. Maybe I'll have to go back to that?!