The specifics have yet to be revealed, however it does appear that Verizon and Motorola are getting ready to begin a soak test for the DROID lineup. This time around the update looks to be heading to the DROID Ultra, Mini and Maxx. And perhaps more important, it is believed to be the Android 4.4 Kit Kat update. What we have seen comes by way of an email from the Motorola Feedback Network and that bit about Kit Kat does involve a bit of speculation.
That being said, Motorola has begun sending out the soak test invites, however as we always see, the timeline wasn't given. According to details coming from the email message, the "start times are always fluid." Motorola then mentioned that users who sign up and don't hear back right away should have some patience.
Anyway, the basic details of the update include the following;
"We are inviting owners of Droid Ultra, Droid Mini or Droid Maxx on Verizon to participate in an early preview of a new software release, and provide feedback."
That aside, Motorola does (as always) have this listed as being confidential and instructs those participating to not post any details or information on public sites. Needless to say, just like the email announcing the soak test, those other details tend to leak in time.
The real questions here are whether this will be arriving as Android 4.4 Kit Kat and how long it will take Motorola and Verizon to work through the process. The timeline for a completion is always dependent on any issues that come up during the test. In previous experience the soak test process can take several weeks, though, Motorola did surprise everyone with a quick soak test and rollout getting Kit Kat on the Verizon Moto X.