Broadcast to Musk's Twitter followers last night (or early this morning, depending on your perspective), the confirmation states simply, "Live pack swap demo on Thurs night at 8pm California time at our design studio in Hawthorne. Seeing is believing."
Musk certainly has that last part right--we'll have to see it to truly believe it.
Tesla isn't the first company to have the idea of hot-swapping battery packs for quicker range extension of an electric car. Project Better Place, which was partnered with Renault, had high hopes for just such a system. Unfortunately, it couldn't bring the reality to market before going bankrupt.
Renault also said, two years ago, that battery swapping is just too expensive to be feasible. The market has changed since then, however, and Tesla has repeatedly proved it can blaze new trails in electric car production, so we have our hopes, especially with more and more Model S electric cars on the road each month.
But we're still waiting until we see it.
For the full read on what may come of Tesla's battery-swapping Model S, head over to Green Car Reports.