Andy Rubin, head of Google’s Android unit, made one of his rare appearances on Twitter today, denying rumors that he’s leaving Google… And as usual, announced new Android activation numbers.

Rubin’s tweet came in response to a rumor floated by Robert Scoble earlier today, in which Rubin was reportedly leaving Google to head up a new startup called CloudCar. Based in Los Altos, Calif., CloudCar is made up of some former Core Mobility and WebTV Networks alums. (Rubin had at one time worked for WebTV/MSN TV before founding Danger Inc., which was acquired by Microsoft.)

Rubin poured cold water on the rumor, however, saying he had no plans to leave. Oh, and by the way — Android now has 900,000 activations per day.

No plans to leave Google.Oh, and just for meme completeness — there are over 900,000 android devices activated each day :-)@Scobleizer — Andy Rubin (@Arubin) June 10, 2012

The activation bit is kind of a joke, since Rubin apparently only appears online to quote Android numbers. Of his 11 tweets since joining Twitter in October 2010, more than half have cited the number of Android devices activated each day. The last number he quoted — 850,000 activated — was during Mobile World Congress in February.

The good news is that daily activations keep going up — although they appear to be slowing down a bit in the last few months, after jumping from 500,000 to 700,000 between June and December of last year, and from 700,000 to 850,000 in the following two months.

And, of course, there’s always the possibility — the probability, even — that Rubin is trolling Apple the day before its annual Worldwide Developers Conference kicks off. Apple execs frequently tout the number of its iOS devices are out in the wild and the number of daily activations during their keynotes. Expect them to do the same tomorrow, especially with a new version of iOS expected to be announced. And expect that number to be dissected and compared against Rubin’s tweet when that happens.