I upgraded to the recently released WordPress 1.5.1.2, so I built RPM packages for the new version:
RPM: wordpress-1.5.1.2-1.noarch.rpm
SRPM: wordpress-1.5.1.2-1.src.rpm
These RPM packages were built under Fedora Core 2 Linux. I have not tested them with other Linux distributions, so they may or may not work in those situations.
I highly recommend you follow the standard installation directions and back up your database and all your WordPress files (especially index.php) before upgrading, as described in the upgrading instructions.