there are 2 types of image stabilizer technology. Lens stabalization and Sensor stabalization.
Take a look at this video to better understand them.
http://www.youtube.com/watch?v=KPdy52mR6Io
Canon and Nikon uses the lens stabilizer. This technology requires the lens to hv stabilizer build into their lens. And due to this reason, the lens will be very expensive, not to mention that every lens u buy, u hv to think hard on whether to buy stabilizer or not, and where to pay extra. And of cos the worse problem is, even if you have tons of money, there are alot of lenses that dont come with stabilizer version.
Sony and Pentax uses a better stabilization technology, the sensor IS. With this sensor Is, the vibration compensation is done on the sensor. As such, any lens that is attached to a Sony or Pentax DSLR automatically becomes an IS lens. It doesnt matter if its an ultra wide angle 10mm lens, or a super old manual focus only lens. They all become IS lens. So if a Sony user buys a 50 year old manual focus lens and mount it onto the Sony Alpha DSLR via adaptor, the lens becomes stabalized. This sensor techology also saves money for the user as they wont have the need to buy IS lens at all. For example, recently Tamron released the VC version of the 17-50mm f2.8 lens which im sure you know, is a popular lens among Canon, Nikon and Sony users. Canon and Nikon users will need to pay $940 to buy a Tamron 17-50 VC lens, whereas Sony users just buy the non VC version for $610 and still enjoy image stabalizer.
Im pretty sure Canon and Nikon can build IS into their camera body. It isnt a new technology. However they will never do something like that, as it will mean a very big lost of profit for them from the sales of IS lenses.