Hi Conrad. Yes, there are different speed methods for a variety of materials. I have only worked specifically with color negative materials, but am familiar with the B&W method and somewhat with color transparency (haven't seen ANSI or ISO docs on that, however). The generally good book, "Basic Photographic Processes and Materials" really only talks about the standard B&W method, but doesn't make this clear; thus one might assume that all materials use this method. Below is a summary of the common film types; I can elaborate more on this if anyone is interested.(posted 8263 days ago)Very roughly, B&W continuous tone neg materials use a speed method where a specified developer is used (they give the formula and aim pH of both developer and fixer as well as agitation method); development time is varied until you get a result such that when one exposure gives 0.10 density above base+fog and an exposure that is 1.30 log(10) greater (this is a factor of 20X more exposure) results in a density 0.80 higher than the lower density. When this condition is achieved, the exposure that produced 0.10 above base + fog is used to get the ANSI/ISO speed.
For color neg materials, the processing is specified by the material manufacturer. So presumably Kodak materials would be via C-41 process and Fuji would be via their equivalent process (I don't remember the name). They have a different method of finding the speed point; it is based on an exposure down low on the characteristic curve (similar to the B&W material); since the three color dye layers don't necessarily hit this at the same exposure level, there is a weighted calculation method. I have read comments by some people that color is not considered in this; they are wrong!
Color transparency materials use a different method based on an exposure roughly midway up the characteristic curve. So it would seem that these should generally correlate better to an exposure meter reading than the neg materials.