From this Salon article:

• 176,000+ members
• 2.2+ million photos growing at the rate of about 30,000 a day
• 82% of the pictures on the site are publicly available

01/03/05 update: Uploading Mayhem: We feel your pain!:

• "The number of images uploaded has tripled over the past two days, January 1 and 2
• Normally we serve about 15 million photos a day, now were serving about 30 million
• About 20 images are uploaded very second; when an image is uploaded, processing it takes a few seconds, because 5 images in different sizes are made, and because we keep live backups on site, each image is each saved onto two different servers"

01/20/05 update: Stewart Butterfield: Growing Pains.