Web tracking firm NetApplications has published data comparing Android and iPhone browsing usage share from launch date and covering the first six months. The trends show that initially Android kept pace with the iPhone initially, but now seems to be losing ground.
NetApplication's take on this is that the Android could be having a hard time moving beyond early adopters.
To be honest, I think that given all the hype surrounding the iPhone when it was launched, combined with all the ad dollars spent on keeping it in people's thoughts, the Android has done pretty well.
That said, moving beyond early adopters is always tricky. That initial rush of the "must haves" is short-lived and in order to succeed technology has to break into the mass market. Android has the potential to do this, but following in the footsteps of the iPhone it has to work harder to grab the attention (and cash) of those looking for a new handset.