Apple delivers third-pary software for scanners and printers via Software Update. Simply connect the printer or scanner to the Mac. If software is needed and available, OS X will automatically download and install it.
This article is a comprehensive list of currently supported printer and scanner models and associated software provided by third-party vendors as of 28 June 2012.
Important: Run Software Update before connecting to a printer or scanner. This will update the Mac's database on the latest supported printer and scanner models.
To view the complete list of printers and scanners that are supplied by Software Update, see below or use the browser's Find feature to look for a specific name or model number. If you cannot find a driver for the specific model, check the list to see if a driver is available for a series of printers that may include the model. For example, a printer with the model number 5070 might use the driver for the "5000" or "5000 Series."
For more information about setting up and using printers in OS X Lion, see this article.
For more information about setting up and using printers in Mac OS X v10.6 Snow Leopard, see this article.
For information about troubleshooting printer setup issues, see this article.