JC, I'm going to reply to your post in pieces.
Quote Originally Posted by jcustis
- If employed properly, IEDs have an almost David-vs.-Goliath quality that facilitates a certain degree of freedom of maneuver, critical to insurgent ops.
IEDs represent simply another aspect of partisan, guerrilla, insurgent, asymetric - call it what you will - warfare. "David-vs-Goliath" has always been the quality of such combat. IEDs exemplify the age-old hit-and-run tactic of the ambush, in that if you are going to categorize them in military terms, you'd have to say they are being effectively employed as a mechanical ambush. In and of themselves, despite the efforts we are directing towards countermeasures, their use does not constitute an RMA. However, that brings us to your next points...
Quote Originally Posted by jcustis
- The powerful imagery of an IED's effects can move around the globe as soon as it is either broadcast on a major news network, or uploaded to a jihadist website. I think that even though the aftermath and ensuing casualties may tell a less dramatic story, the initial shock of the image at detonation is so powerful that it has reached virtually every insurgent/terrorist group around the world. As a result, the how-to of complex IEDs may not have reached other groups, but I believe the IED will become a "keeping up with the Joneses" concern for groups if they do not already possess it the capability.
I think the key to the quote above is the statement you made at the end of your post: "Is the IED just one component of a larger RMA in the works?". Yes, and that larger RMA is the Information Revolution. There has already been a great deal posted on SWC regarding how the bad guys exploit the internet and other new communications technologies to facilitate their ops, spread their ideology, and distribute TTPs.

Years ago, Hizbollah began exploiting media with regards to IED attacks by having a cameraman with the individual initiating the device film the incident to show on local TV the same day. Now, that propaganda effect is multiplied exponentially by the bad guys' ability to post the vid on the 'net for viewing worldwide just as soon as they can upload it.

But that's just the propaganda piece - it goes well beyond that. I already discussed how modern communications tech facilitates dispersed, compartmented cellular ops in the post above yours. But, as you're already aware, it also facilitates sharing of TTPs with non-related groups to a degree not seen before. Insurgents, terrorists and revolutionaries in Asia, Latin America, and Africa - as long as they have 'net access - can exploit lessons learned in Iraq fighting against the world's superpower and put it into even greater effect in their own AO. This has the potential to provide a qualitative evolutionary leap in ops to a nascent or struggling group. As you stated, the material requirements are not great (and IEDs do not need to be "complex" to be effective). But the only thing in favor of regimes facing such a potential threat is that it requires a certain degree of intelligence and previous operational experience in order to effectively apply those TTPs in a new context. Thus far, we've only seen relatively limited threat migration. But I don't expect that situation to last.

Finally, as an aside:
Quote Originally Posted by jcustis
- We should expect to see IEDs on any future battlefield (Conventional and UW). I firmly believe that if IEDs had been employed with the same tradecraft during the March Up as they are now, we might still be making that movement to Baghdad.
I concur in that we must take IEDs into consideration in the planning stages for any future op. However, I disagree with you on the point about the March Up to Baghdad. IEDs are not very effective against a rapidly advancing combined arms maneuver force on a conventional battlefield (even if they have to deal with unconventional attacks en-route to the objective). Once that force occupies the objective, and has established patrol routes and static areas of responsibility in the effort to establish post-conflict stability and security, then it becomes vulnerable to IEDs.