A picture of one of Apple's mysterious vans. (Republished with permission from Claycord.com )

The photos were first snapped and posted to the  Claycord.com local news blog on Tuesday. The site, which covers local news for several cities in northern California, said that the person sitting in the vehicle "would never give an answer" about what they were doing in the car. A subsequent report from San Francisco CBS affiliate KPIX 5 confirmed that the car had been leased to Apple.

Apple declined to comment.

There are two main theories at work now about what Apple's planning with these cars. The technology on the rigs, as Apple Insider has noted, is consistent with the type of technology that Google and others use for mapping services. The other, more far-fetched, conclusion is that this may an Apple entree into the world of self-driving cars.

Those are two pretty different theories --  one safe and one a little crazy. Let's take them on.

It would make a lot of sense for Apple to look to improve its mapping services. The tech giant famously jumped into the space with a service based on  TomTom's maps in 2012. The results were sub-optimal, to say the least. At a time where Google was working on mapping the ocean floor, Apple Maps was having trouble even finding, oh, any location in Japan. A formal apology, lots of work and two years later, the service has improved, but it's still far from parity with Google.

It would be particularly helpful for Apple to update its real-world view in maps, which is similar to Google's "Street View" images. Lacking that feature -- Apple does have satellite imagery and some 3D maps, but it's hardly the same -- arguably limits the Apple Maps audience. Street View is pretty useful for pedestrians, for example, or for businesses such as real estate agents who want an easy way to show off their properties. Amassing that kind of information would be difficult for Apple, but it would put the company on more equal, competitive footing with Google when it comes to maps.

And then there's the theory of a self-driving car.

In its reports, KPIX 5 quoted technology analyst Rob Enderle as saying that the rig has "too many cameras" -- more than it would need simply for mapping -- and speculating that Apple may have a partnership with an automaker. Others pointed out to the Claycord news blog that the roof-mounted contraption bore a resemblance to what Google has on top of its own, well-publicized self-driving car prototypes.

Still, the rumor calls for a lot of skepticism. While Apple executive Phil Schiller did once say in 2012 that the firm had thrown around the idea of making a car before the iPhone, the company  has never demonstrated real interest in it. As Business Insider noted, the idea of a car came up as Apple was considering "crazy" stuff to develop -- there's no indication it ever got far.

Apple is interested in cars, of course, but right now that seems limited to the dashboard. Apple CarPlay, for example, allows users to plug their iPhones into their cars and use iOS-like menus to pick music and look at maps, extending Apple's grip on the smartphone world.

That product is still in its early stages and, to date, seems to be the extent of Apple's interest in automobiles for the moment. There's been no serious indication from the company that it's looking to move its focus outside of the cabin -- not even, as Patently Apple noted earlier this week, in its patent filings.