A RIMS or HERMS setup is pretty common, which in layman terms is a system that enables increased ability to contol mash temp. Such systems are perhaps more common in America where they have the resources etc. I would guarantee that some of the guys on the forum have a setup like this, but i'm reckon most guys here are with the KISS principle where they use a esky instead of such a system, check out the gallery to look at other peoples systems.
The things that intriguing on this site, is that the kettle is a steam jacketed kettle. Whilst this is common in commercial breweries i have never seen a person use a steam jacketed kettle on such a small scale setup, especially one that was home made (sounds scary)
Using steam to step mash etc seems to raise its head fairly often on American Forums, there seems to be mixed views of it. The normal view is that they have seemed to have figured out that the system is limited to 23-35 litre batches, any more and that when the system starts to be less effective.
I've seen a US site where the steam outlets are doubled with a stirrer, so that two birds are killed with one stone.
Another thing you may consider, is instead of using a pressure cooker you could use a wallpaper steamer, which the SIMM guy uses
""A fully enclosed system using pressurized steam", that was exactly
what I wanted. And I knew where to get one. Lucky for me a local tool
rental company was going out of business and I was able to get a
great deal on a...have you figured it out yet? A wallpaper steamer!
It's perfect, I just fill it with water, plug it in, wait about half
an hour, and I have steam delivered safely at 12 psi. via a rubber
hose with standard air hose quick connect fittings." (http://hbd.org/hbd/archive/4586.html#4586-4)