If I may shed my light on this matter / rumor. I'm not really that educated on operations management (only had a 1300 page course on it) so bare with me. But, to me, it makes no sense to pin-point the introduction of a hardware revision like this. You people really think Apple is busy manufacturing iPhone 4A units and then, boom, switches production and manufactures B (revised) models all of a sudden? That makes no sense and would be quite risky. It's not like they are just adding different chips here or something.
If you get your hands on a new iPhone 4 now: I'm 99% certain that it was manufactured only a week ago. If Apple is holding back revised models we'll see a obvious decline in iPhone 4 shipments this month because there is no way they are going to just switch the whole production over to model B all of a sudden. It just doesn't make sense: they should already be running some batches now and we would be seeing those already in stores by now / next week. At least we would see those emerge over time (same happens with those Xboxes / PS3's switching to smaller CPUs). Remember: Apple can prototype all day long, in the end it all comes down to a final product, out of a batch of 10.000's of phones...
Also, the internals of these types of hardware (smart phones, computers, consoles etc.) iterate all the time. They would change some things to e.g. batch 1220, while leaving batch 1221 and 1222 unchanged. Just to test run the production line over longer time. They will be producing model B devices in parallel of model A devices.
So, if there is going to be a hardware revision (which is even (un)likely), we will see these new revisions emerge over time. Unlike: 'It's 30th september guys: boom, and now everything is a revision B model. That scenario only make's sense if we see a big drop in iPhone 4 supplies because it would mean Apple is holding back the revised models they are manufacturing already.
So, are we seeing a big drop in iPhone 4 shipments? Have these revised iPhone 4 models already been spotted in the wild? I guess not...
