You can do this:
add-pssnapin Microsoft.Exchange.Management.PowerShell.E2010
and most of it will work (although MS support will tell you that doing this is not supported because it bypasses RBAC).
I've seen issues with some cmdlets (specifically enable/disable UMmailbox) not working with just the snapin loaded.
In Exchange 2010, they basically don't support using Powershell outside of the the implicit remoting environment of an actual EMS shell.