What are the advantages of Python, PowerShell, and other scripting environments?  We would like to standardize our scripting and are currently using bat and cmd files as the standard.  I think Python would be a better option than these, but am also researching PowerShell and other scripting tools.
The scripts would be used to trigger processes such as wget etc to call web services, or other applications/tools that need to run in a specific order with specific parameters.
We primarily work with the Windows stack, but there is a good chance we will need to support Unix in the future.
We would like to standardize our scripting and are currently using bat and cmd files as the standard.

It sounds like Windows is your predominate environment.
If so, PowerShell would be much better than Python.  

PowerShell is included with Windows
Server 2008. No need to
deploy/install Python runtime on
every new server that rolls in.
The entire Microsoft server related software (Exchange, Systems Center, etc) is transitioning to PowerShell cmdlets for functionality and extensions
3rd party vendors (e.g. SCOM plugins) will also use PowerShell scripts/cmdlets to expose functionality

I have more experience with Python than PowerShell but the writing is on the wall as far as the Microsoft ecosystem is concerned:  go with PowerShell.  Otherwise, you'll just be going against the grain and constantly interop-ing between Python and everyone else's cmdlets.
Just because you can code import win32com.client in Python does not put it on equal footing with PowerShell in the Windows environment.
Python, PowerShell, or Other?