Microsoft has released a quick-reference guide to commonly-used Windows PowerShell Script commands.
Windows PowerShell Scripting Guide
This guide provides a quick reference on how to read a text file, write conditional statements, write a text file, write for and for each loops, write Do Loops, access arguments, use colored text, insert a paragraph return, make comparisons, create multi-command lines, insert line breaks, solicit input, insert commands, print data, create a COM object, create a .NET object, work with WMI, bind to active directory, select properties, sort data bind to local accounts, get Help, Copy and Paste, run a script, change security settings, interrogate and object, clear the console, and so on.
Download: Windows PowerShell Guide from Microsoft.
For more information on writing Windows PowerShell scripts visit the TechNet Script Center.