I've downloaded RC5 today, and tried to get it running on my machine (Apache 2.50, PostgreSQL beta5, PHP 5.03). The install.php appears, but whatever I enter in the database setup the connection always works - and when I start installation (even with valid username/pw) I just get a blank page. I could track it down to:
(~line 180 in Install.php)

$db->query(stripslashes($do_query));

This line doesn't get executed, if I add an echo before it, it works, if I add an echo after it, it doesn't get displayed. Seems that the problem is with the db connection, though I'm not sure (no time to debug). Any ideas what might be going on?
I also tried dumping the output (i.e. the stuff that should be passed to the db) and add it on my own to PostgreSQL (using the PGAdmin III), but this failed due to an error in the transaction.

Cheers, hope I can sort that out asap.