To quote the completely understated download blurb:
Windows PowerShell V2 CTP3 introduces several significant features to Windows PowerShell 1.0 and Windows PowerShell V2 CTPs that extends its use, improves its usability, and allows you to control and manage the Windows environment more easily and comprehensively.
The release notes are quite extensive. Here is the section on breaking changes from CTP2:
Breaking Changes to Windows PowerShell V2 (CTP2)
The following changes in Windows PowerShell V2.0 CTP3 might prevent features designed for Windows PowerShell 2.0 CTP2 from working correctly.
"Script cmdlets" have been renamed to "advanced functions." The “cmdlet” keyword has been replaced with the “function” keyword. For script cmdlet functionality, use CmdletBinding attribute in the function’s param block. For more information, see about_functions_advanced.
Note: If you have upgraded from the Windows PowerShell V2 CTP2 release to the Windows PowerShell V2 CTP3 release, to configure your system for WS-Management remoting, type:
Unregister-PSSessionConfiguration * -force;
Register-PSSessionConfiguration Microsoft.PowerShell –force;
The name of the application has changed from “Graphical Windows PowerShell” to “Windows PowerShell Integrated Scripting Environment (ISE)”
The executable name has changed from “gpowershell.exe” to “powershell_ise.exe”
The profile name has changed from “\Users\<username>\Documents\WindowsPowerShell\Microsoft.GPowerShell_profile.ps1” to “\Users\<username>\Documents\WindowsPowerShell\Microsoft.PowerShellISE_profile.ps1”
The term “runspace” has been replaced with “PowerShell tab”.
Get it from http://www.microsoft.com/downloads/details.aspx?FamilyID=c913aeab-d7b4-4bb1-a958-ee6d7fe307bc – piping hot!