A source close to Apple has stated that the blackout on employee vacation requests is indeed related to the Apple launch of their unlocked iPhone 4 product on Verizon, which will reportedly come on February 3rd. The deal has been one that has been long awaited, and has been rumored to be on the near horizon for quite some time. Of course, this has never materialized leading some to believe that it may never happen. Now, with the blackout on the horizon and no explanation being released for it, it appears that Apple is going to keep quiet about the launch until some point at the Consumer Electronics Show. Their announcement should overshadow just about any other announcement at the show and will create a lot of hype. Verizon users have been eagerly awaiting the release of the iPhone, and it finally seems as if it is coming to fruition.
The Verizon iPhone has no information out there about it currently. Some have speculated that it could have additional features that would make it a more worthwhile purchase, but no information about that has been released so far.
The blackout only applies to individuals that work in the retail stores and does not apply to employees with seniority. If the iPhone is indeed what is causing this move, it is likely because they are expecting a huge turnout in the days leading up to and following the release. There is no doubt that the iPhone will be abundantly popular on the iPhone 4 unlocked, but Apple certainly seems to think that they will need all hands on deck to deal with the response.
Now, we have to wait for an official announcement from Apple. With all of this speculation, it will be hard for them to keep it quiet for long, especially with insiders already talking to the media. Expect the announcement to come at some point in the near future.