It's looking like Firefox 3.6 will miss its 2009 release goal, but the browser should arrive shortly after the start of the new year.
Firefox 3.6, currently in the final beta-release stages, will arrive in the first quarter of 2010, according to Mozilla Wiki. The slight delay is having a ripple effect, however, because future Firefox releases have been rescheduled as well. Mozilla has already pushed back its road map for both Firefox 3.7 and 4.0.
Once Firefox 3.6 is out the door, Firefox 3.7 (a fairly minor, incremental release) shouldn't be too far behind, but we may have to wait until 2011 before the next major revision roles around. According to recent Mozilla meeting notes, Firefox 4.0 won't come around until late 2010 or early 2011.