After months of using Windows Server 2008 and watching as many (most) of the Microsoft infrastructure arsenal began the migration to PowerShell, it seems that the net effect is that everything is returning to where it began: A GUI on top of a command shell.
Many people mistakenly think that it's always been that even through Windows NT, 2000, XP and into Vista. But that's dead wrong. NT4 was the turning point where the GUI (or GDI underpinnings) were the kernel master process and CMD was a child process hanging off of it like Remora on a Shark. This arrangement has remained in place, in fact become more tightly engaged with the NTOS kernel, that to see it turning around to PowerShell is really quite a surprise. I don't think it was the original intent when Jeffrey Snover and the gang started whiteboarding this thing. I think it was first envisioned to be a replacement for CMD.exe and many interviews I've seen seem to back that up.
Then came Exchange 2007 and the announcement it would be built "on top of" PowerShell. That got a little attention, but then came WS08 Core and the talk about getting PowerShell into that environment. Now with the additional announcements that System Center products (such as SCVMM, SCDPM and SCOM) would not only support PowerShell, but that it would be tightly integrated, were enough to stick a snake prod into the hind parts of EMC. Now Virtual Center is making a ton of press with scripting feature announcements, and this is all a good thing. Competition keeps it all working for us as customers. Every single product or service I've seen that lacked real competition ends up sucking horribly. I dare anyone to show me one product that really rocks which doesn't have some competition keeping it on it's toes. It's a part of nature.
I doubt that Windows 7 or Windows Server 7 will be built "on top of" PowerShell, but who of us really knows? With Steven Sinofsky in charge, it's going to be much quieter on the W7 front. If Sinofsky had his way, it would be more baren of "news" than anything Apple would dream of in the information restriction camp. I'm pretty sure though that W8 will have significant incorporation of PS features. I'm glad Linux and OSX are doing well, this keeps Microsoft drinking coffee and staying up late. We benefit from all three.