One disadvantage when I switched from a
Canon 400D to a 40D was that the former uses a small and dirt-cheap ($20) RC-1
InfraRed remote control whereas the 40D uses the much larger
and expensive ($300!) LC-5 wireless remote control.
But after poking around a bit, I found a compatible Canon wireless remote
control that is sold on eBay under the brand name Phottix by HKSupplies
for about $35 (including shipping) that works great. While I don't use
it too often, it has worked well when I have, plus you can't beat the price!
There are 4-dip switch settings that allow you to set a semi-unique code. Basically plug the receiver into the camera (Canon 40D below - see second picture) and turn it on. A red light goes on ... and then simply press the transmitter to take a picture and green lights will go on both units. As seen in the last picture (1 second hand-held with my Canon SD800IS P&S), it works from over 500 feet away - 9 outa 10 times from here. BTW, you can press halfway for exposure/focus - i.e. this is a dirt simple/easy-to-use Canon wireless remote.