The New York Times today reported  on a recent Hitwise post  by Heather Hopkins highlighting that Google was now sending about three times as many of their users over to Google Maps comparing a week ending January 6th with a year ago.
This is apparently due in part to Google recommending Google Maps instead of recommending other mapping providers in addition as it had been doing early last year.
But, another factor that I think must be involved is Google’s Universal Search which appears to be suggesting Google Maps results more frequently for a variety of search combinations.
They’re undoubtedly keeping searchers more sticky on the Google properties.
Mapquest is still leader among mapping providers. Interestingly, if Mapquest was impacted by Google’s more aggressive retention of map consumers, it was only a fairly negligible impact — Mapquest usage didn’t appear to decrease by the same amount that Google Maps increased, according to the Hitwise graphs. This would suggest to me that Google was perhaps persuading more of their users to visit Google Maps than what would have otherwise happened had they not been so actively promoting their Maps content.
Reportedly, an additional factor pushing up Google Maps usage was the advent of the iPhone.