ISE may be started from the start menu; however, running the powershell_ise command (from the Run dialog, cmd, or the search box) is sufficient. In PowerShell, the simpler ise command is aliased to powershell_ise.exe.

If the preview version from the PowerShell gallery is being used, the following command will start that version of ISE:

Start-ISEPreview 

This first preview version differs a little from the version of ISE shipping with WMF 5. If the distribution model is successful, the PowerShell team hopes to release a new version of ISE every month, with each release fixing bugs and/or adding new features.