Barack Obama's website is reporting that the campaign reached 1.5 million donors last night, just in time for the Indiana and North Carolina primary. The campaign has not yet publicized the milestone, though it is mentioned in their blog.
From the Obama blog:
On the eve of the Indiana and North Carolina primaries, we reached another incredible landmark: the 1,500,000th person made a donation to this campaign.
This has been an incredible journey so far. Along the way, we've heard from countless supporters who had never donated to a campaign before now, and inspiring stories of people who have challenged themselves to donate, to organize, to canvass and call to help build this movement.