Just one thing to be wary of, if the wireless shutter releases mentioned above are the same ones as those found at
http://www.gadgetinfinity.com/ - These shutter releases will cause MAJOR problems if you also want to use the wireless flash triggers from the same vendor, as they both operate on the same frequency.
Both the flash triggers and the shutter triggers don't actually have multiple channels, they have multiple code sequences that are called "channels" even though they are all on the same channel.
Right now I have a homebuilt cable release (search for Pentax on
Instructables - How to make cool DIY projects), which includes a 1/8" mono jack in parallel with the momentary and toggle switches for the shutter. This allows me to use the Gadget Infinity flash triggers to trip my shutter. (Because the flash triggers are "one shot" as opposed to continuously transmitting to support bulb mode, they don't have the interference problem with another set of triggers used for flashes that the shutter triggers which support bulb mode have.)