I installed it as my admin user not as root. It installed just fine no problems whatsoever.Originally posted by CerealKiller
You should log in as root to install Developer.pkg. Don't just enter an administrator password. The installation will proceed to 1/2 way and simply stop. The dialog will remain, but the software will never completely install.
If you log in as root, it'll almost completely finish the installation but not quite. At 1/2 minute remaining it'll stop installing. There has been lots of debate (here and on Apple's discussion boards) but no real answers yet.