This all depends on what you mean by "native ISO sensitivity".
If the implication is that the sensor itself has a native sensitivity, the result of some unique gain of the amplifiers that precede digitization, leading to a unique sensitivity, and that we then change the gain of the amplifiers to depart from that, this is a misconception. There is no magic gain value that we can depart from. There is no sensitivity of the photodetectors until they have been provided with some gain (which could be 1.0) between their output and the input to the analog to digital converter.
In that vein, if a sensor has amplifiers that can be set digitally to give (only) gains that result in the ISO sensitivity being, say, ISO 100, ISO 200, ISO 400, ISO 800, and ISO 1600, then we could (if we felt a real need to use the phrase) say that all of these are the "native ISO sensitivities" of the sensor.
Now, in a particular camera model, the manufacturer may elect to provide ISO sensitivities other than those provided by the available repertoire of amplifier gains by scaling the digital outputs, using digital arithmetic, by various factors, thus establishing intermediate ISO sensitivities. It appears as if the intermediate sensitivities of the EOS 30D are attained that way.
Those intermediate sensitivities have some disadvantages with respect to saturation level and the like (perhaps leading to compromise in dynamic range or "posterization"), which have been discussed at some length in various forums.
Perhaps one could choose to say that these ISO sensitivities are not "native sensitivities" of the sensor. I find no attraction in the phrase.
A distantly related issue is whether the various ISO sensitivities are stated in accordance with the ISO standard for determining and stating the ISO sensitivities of digital cameras. As has been mentioned here, it appears that the sensitivity designated by Canon "ISO 100" would actually be properly described as perhaps ISO 125 or ISO 135 if determined and stated in accordance with that ISO standard.
I presume that this is a means of Canon having their cameras depart form the "standard metered exposure" prescribed by the interaction of two ISO standards, that for the "calibration" of an in-camera exposure metering system and the one for the designation of ISO sensitivity.
The doctrine set forth by the interaction of these two standards allows about 1/2 stop "headroom" to avert overexposure of the highlights in the case of a scene having a low average reflectance (assuming that the metering system is a basic ("dumb") "average luminance" system.
Very likely, since the centerpiece of Canon's metered performance is their Evaluative metering scheme, which uses an intelligent algorithm to predict, among other things, what the greatest luminance in the scene probably is, Canon may feel that this "headroom" is wasted. They could crank that out by changing the "calibration" of the exposure metering system itself. But if they did that, then photographers using an external exposure meter (one calibrated to ISO standards) would get a different exposure recommendation than that which would be given by the camera's metering system, a sure cause of consternation.
But instead, Canon could have chosen to understate the ISO sensitivity of its sensor, The result would be a standard exposure doctrine that "recovers" the headroom, while keeping apparent consistency between the cameras; metering system and external meters.
That is of course just conjecture on my part.