As users do more computing on their Smartphones it's inevitable that the demand for printing from them will grow. E-mailing a document to yourself and retrieving it on your laptop or saving to a microSD card and then using a reader to access that card from your laptop or desktop both work, but they're clunky, as is transferring from the handheld to your computer via a sync.
An adapter can give you printer access via Bluetooth to a USB or parallel printer. The gadget will work with any Bluetooth device, not just smartphones, so you can also use one to print from a laptop without a physical cable.
Belkin's F8T031 and HP's Bt450 are both billed as Bluetooth Wireless Printer Adaptors and should work with many different printers. AbiCom also makes an adaptor, but it's specifically designed for certain USB ink jet printers.