I was surprised Android wasn't a higher percentage... Look at it this way:

78% of the current smartphone market is Android, 18% is iOS. [1] (4.3:1 in favor of Android)

According to the article, 38% of hackathon devs are interested in Android dev, and 22% are interested in iOS Dev. (1.72:1 in favor of Android)

From this perspective, desire to develop for iOS is MUCH higher than market representation, meaning that (as I read the numbers) comparatively, Android appears to be the weaker choice -- and that amongst hackathon developers, iOS is far over-represented compared to the market as a whole, as I assume most at these events use their own devices.

[1] http://www.idc.com/prodserv/smartphone-os-market-share.jsp