So if UAC is not a security boundry, then its purpose is to annoy the hell out of me, right?

It should be clear then, that neither UAC elevations nor Protected Mode IE define new Windows security boundaries. -Mark Russinovich on his blog.

I grew immune to the UAC prompt after only a few hours. I didn’t even care anymore. I have a great respect for Mark. Before he was a “Technical Fellow” at Microsoft, he developed the very cool (albeit useful) SysInternals tools. Yet I get tired of the MS chant of “UAC uber alles” and posts like his.