Some say July, but I think November 2010 - January 2011 is a better bet based on the time it took for the 2.1 update to be released. Verizon is extremely slow at releasing updates. They also do not seem interested in keeping customers informed about updates either...
It was leaked yesterday that the Droid is slated for late July and the X will get it in late August but everyone knows verizon doesn't really stick to the rumored dates.
It goes like this. Yesterday Google finally released the full version of Froyo. Making it officially announced before making the final verison seems like an odd move but whatever. Supposedly it started rolling out to Nexus 1 phones. According to Motorola the Droid will get Froyo first in July followed shortly by the Droid X and then on down their list. Which leads me to wonder if they are going to abandon the rest of the 2.1 listed phones and try to get them 2.2 instead. At this point I would be worried about just how far down on the priority list I was if I had one of those phones. Anyway, Motorola will or has gotten the source for this completed version. Since the Droid is Vanilla Android all they have to do is modify their patches to make the most of their hardware and the new software built in. Since the OS has changed it will require a good examination of the OS as it stands and evalutation and discussion of how to best fit everything in. (or they will just port the drivers and let the rest sort itself out). Then it will be tested by their engineers, once it passes it will be tested by Verizon. Verizon will make their recommendations and probably change the way the built in tethering works somehow and make a few other "system preserving" recommendations Motorola will make those changes then resubmit. Verizon will test and probably pass it unless some major flaw arose. Then it will be passed to the third party that manages the rollout. They will have to configure their system to back everything up wipe the phone and then reformat everything then bring the data back over. They will develop a schedule. If everything goes well there will only be a few delays with the process and/or system issues and hopefully they will only have to fix the problem with backups not happening right once and off to the races. July seems quick but it is far more specific far earlier than we ever got with 2.1 so no worries. The Incredible won't even have rumors HTC is far to tight mouthed to let anything slip. One day we will just wake up with a notice.
Hopefully Android 3.0 (Gingerbread) will help alleviate the lag resulting from the manufacturers making it work with their own custom UI. Google wants to make is so that various UIs aren't really needed but I guess we'll see how that goes.
PC Magazine reported on 7/3 that Froyo should drop to the Motorola Droid within the next two weeks - so this should be by 7/16ish. Then the Droid X will get it next.