Microsoft-Watch reports that Panther is still on track for a September release.
According to the report, initial plans placed Panther "gold master" in late August with delivery in mid-September. This appears to have been pushed slightly back with "gold master" planned for early September, with a full release within that month.
Development on Panther has continued at a steady pace since WWDC, with a number of new versions becoming available to developers. Most recent reports have hinted that the operating system is approaching its finished form.