Andy Rubin, the head of Google's Android efforts, tweeted on Monday that the Android platform has reached a major milestone: 500,000 new Android handsets are activated every day. Google announced just two months ago that Android activations had hit the 400,000-per-day marker. Rubin also noted that Android's growth rate is increasing at the astonishing rate of 4.4% week-over-week.

This explosive growth rate puts Google on track to activate 1 million Android handsets per day by the end of October.

The adoption rate of Android is far outpacing that of rival iOS. Apple is seeing about 210,000 iPhone activations per day, and about 325,000 iOS device activations per day if you include the iPad and iPod Touch.

There's a lot behind Android's amazing adoption rate. Handset makers have stepped up, delivering an unending stream of low-, mid-, and high-end Android smartphones that cover almost every conceivable market segment and need. Wireless network operators are doing their part, too, supporting the platform with massive marketing campaigns (look no further than Verizon's "Droid" advertisements).

While this is no doubt a stunning feat, Google's penetration into the enterprise is marching forward a bit more slowly. Strategy Analytics recently reported that while Android and iOS adoption in the enterprise is growing, Research In Motion's BlackBerry platform still has the most widespread support from businesses. It reports that 42% of U.S. businesses have adopted Android, 49% have adopted iOS, and a commanding 72% have adopted BlackBerry.

"In contrast to the relatively modest, but growing level of reimbursement for BYOD devices, the exponential growth in enterprise support for iOS and Android suggests that Apple and Android devices and supporting ecosystems are gaining credibility in their own right as corporate standard-issue with appropriate levels of IT support," commented Andrew Brown, Strategy Analytics' director of wireless enterprise strategies service, in the report. "Nevertheless, IT policy management remains a challenge, suggesting a major opportunity for mobile device and application management solutions."

Android's smartphone market share in the U.S. surged to 36.4% during the first quarter of the year, according to ComScore. Android's share dramatically leads the iPhone's 26%, RIM's 25.7%, and Microsoft's 6.7% market shares.

Globally, Gartner expects that in 2012 about 315 million Android smartphones will be sold -- representing half the market. Apple's will be a distant second with just 18.9% of the market.

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