Here's the information from Microsoft:
"... With PowerShell 1.0 on Windows update, we will now be reaching a broader audience, a lot more than our 3.5 million downloads so far. This is our second step in making people ready for PowerShell and the rich set of features in 2.0 when they deploy Windows 7 or our WTR. Also, this release sets an expectation that the WTR of PowerShell 2.0 would be pushed through WU/MU/WSUS for enterprise deployment.
PowerShell 1.0 through MU is only offered:
· As an optional update
· If you don’t have any other version of PowerShell installed (including V2 CTPs) on your machine
· .NET 2.0 is installed on the machine
· OS is one of: XP-SP3, W2K3-SP2, Vista-RTM, Vista-SP1 ... "
PowerShell is here to stay!!