AppleInsider thinks so. According to their report the newest build, “9E17” has no known issue and that only two fixes have been in the last 10 days.
The article suggests that we’ll see 10.5.4 before July 11th, because of a need for the system to integrate Mobile Me support into OS X.
I think its highly likely we’ll see some kind of update in the very near future. I seriously doubt Apple is going to go through this much trouble to rebrand the .Mac service without issuing an update to change it throughout OS X as well.
I’m hoping that we not only see 10.5.4 by then but early July for Mobile Me and 2.0 firmware has more emphasis on the “early” part of July instead of closer to mid-July (i.e. 11 July).