If Facebook is any indicator, it looks like Windows Phone has seen a significant boost recently. Since Christmas, the number of Facebook users connecting via WP7 has increased by 200 thousand. The figure now stands at 1.3 million users total. While Windows Phone Facebook usage has steadily increased since WP7's launch, this bump looks to be the most dramatic yet.
WMPoweruser has used the numbers to make a shaky estimate of 8-9 million Windows Phones devices out there in the ether. We're not sure how accurate that number actually is, but it would be swell if that were indeed the case.