The very last entry in the HardyReleaseSchedule page states:
July 3rd Ubuntu 8.04.1
This is Hardy with all the updates since 8.04 was released three months ago; the .2 release will be in six months (three months after 8.10 is released).
[Edit July 3: The release announcement has been made; its out so grab a copy! The most notable improvement IMHO is that "Firefox has been upgraded to the final 3.0 release from Mozilla" but there are lots of other improvements too :]