I can't really say, because we haven't done much testing on Android yet. My understanding is that Android's WebView uses a webkit rendering engine, but generally has poorer performance than the iOS UIWebView. So my guess is optimizing for iOS won't necessarily hurt anything for Android, but Android won't have quite as good of an experience. Hopefully this will get better with time... the UIWebView performance increase we saw from iOS 4 to iOS 5 is encouraging.