Excerpt:
...One example that's relevant to the CDN market is the One Pica Image CDN extension. One Pica strives to build scalable and flexible enterprise systems for all of their clients, large and small, and to give back to the Magento community to promote its success.
The One Pica Image CDN extension enables Magento's customers to host category and product images on a CDN with ease. The extension automatically distributes category and properly-sized product images to a CDN when they are referenced in the Magento templates. This code extends the functionality of category and product image getUrl() to determine the existence of the file on the CDN, push the image to the correct location if it isn't found, and return the CDN-specific URL. Installation into an operational store will work immediately as images already present will be uploaded to the CDN on demand. As a result users can install, enable, and disable the extension without consequence and at any time. Changing from one CDN provider to another is relatively easy - the user simply alters the extension settings within the Magento eCommerce platform.
The extension currently integrates with the following CDN’s: Amazon S3, Coral CDN, Mosso/Rackspace Cloud Files, and any CDN, server or service that supports FTP, FTPS, or SFTP. Integration with Amazon's S3 service includes and uses the wrapper called PHP-AWS. The Mosso (now called Rackspace Cloud) integration includes and uses the wrapper written by Mosso. Coral CDN is a free, open source, peer-to-peer content distribution network that works simply by appending ".nyud.net" to the hostname of any URL. The FTP/FTPS/SFTP integration utilizes the respective PHP wrapper...
Full Article: http://www.cdnexpertonline.com/node/47
Magento Extension: ImageCDN Magento Extension
