In addition to the 16 regressions of the highest priority for GCC 4.5, there are 98 regressions marked as P2 and 3 of P3 status. In today's GCC 4.5 status update, Richard Guenther pleads with the GCC developers to work on any assigned P1 regressions or un-assign yourself from them, otherwise those regressions will be downgraded to P2 so that this new release can be made. While this release is taking a while and the regression count isn't dropping sharply, Richard adds, "Overall GCC 4.5 does not look bad."
With GCC 4.5 the MPC library has been integrated to evaluate complex arithmetic at compile time more accurately, a new link-time optimizer has been added, automatic parallelization can be enabled as part of Graphite, improved experimental support for C++0x, Windows improvements with Cygwin and MinGW, and many other changes.
Most of the Linux distributions that are shipping major releases in H1'2010 are shipping with GCC 4.4.x due to GCC 4.5 not being ready, but openSUSE 11.3 is one of the few that is already packaged with a GCC 4.5 snapshot, but that Novell-sponsored distribution will not be releasing until July.