The first GCC 4.5 release candidate will be made once there are no longer any P1 regressions remaining. As of this morning, of the P1 regressions there were 26, 93 regressions of P2 priority, and then just four P3 regressions. This is the first status report on GCC 4.5 since this past September.
Today's GCC 4.5 status report can be read on the GCC mailing list. GCC 4.5.0 should be released at some point in 2010.