Windows 8.1 and Windows Server 2012 R2 both include significant enhancements to the PowerShell scripting environment and language, but what if you want to try out those options on an older system? The newly-released Windows Management Framework 4.0 preview lets you test out those features on Windows 7, Windows Server 2008 and Windows Server 2012 releases.
This is definitively a preview release not suited for production environments; there's no planned upgrade path for when the final release comes out (at that point, you'll have to uninstall and reinstall). It's also not compatible with servers running Exchange, SharePoint or Small Business Server. Check the blog post for full details, and happy scripting.
Windows Management Framework 4.0 Preview Now Available [Windows PowerShell Blog]