Google Earth 5.0 was released today, with a bunch of new features. The ocean layers were not unexpected: ocean floor bathymetry was released a couple of weeks ago (see Stefan’s critique), and the previously announced presence of Sylvia Earle at today’s launch (CNet, Google Earth Blog) telegraphed the focus of this release.

But completely unannounced and a bit of a surprise is a separate “Mars mode” (accessible from the same drop-down that toggles Earth and Sky). I would guess that, thanks to so much new and astounding imagery from sources like the Mars Reconnaissance Orbiter, a high-resolution digital globe of Mars is finally possible — as opposed to the low-res, in-browser Google Mars (previously) or layering another planet’s imagery atop the Earth.

Other features, briefly noted: access to historical imagery via a slider, which will be dependent on how much older imagery exists for a given location; and the ability to record tours.

Update: My bad: Mars is mentioned in the Google Blog post.

Update #2 (5:53 PM): On the historical imagery feature, see Google LatLong and the Google Earth Blog.

Update #3 (10:04 PM): Reviews are coming in: CNet, Ogle Earth.