I came across this feature browsing topics in "Printing & Fax help," directly withing Apple help:
Creating a printer pool[robg adds: I don't normally run hints that are present in Help, but a quick survey of some friends showed that none of them (nor I!) were aware of this interesting feature, so here it is. To read the original, open Apple Help and search on "pool printer" (no quotes).]
If the printers you use are often busy and you want to print a document as quickly as possible, you can create a collection of printers, called a printer pool. Your document automatically prints to the first available printer in the pool.
- Open System Preferences and click Print & Fax.
- Click Printing, and then click the Set Up Printers button.
- Select the printers in the Printer List that you want to be in the pool. (Select the first printer, then hold down the Command key and click additional printers.)
- Choose Printers > Pool Printers.
- Type a name for the printer pool in the Printer Pool Name field.
- Drag the printers into the order you prefer. When you print, your computer will check the first printer in the list for availability, and then the next, and so on. The printer options for the printer pool are taken from the first printer listed in the printer pool.
- Click Create
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040107135609876