iStockphoto introduced a plug-in for Aperture 1.5 on Tuesday. The iStockphoto plug-in takes advantage of the new plug-in API in Aperture to let you batch-upload image groups from your image library to the iStockphoto Web site. It also automatically uploads attached metadata and keywords with the images. The plug-in is free, and available for download at the iStockphoto Web site.