Hi Zemi,
What happens when you run a command in the shell? Also, are you launching the Windows Powershell, or the Exchange Management Shell? For Exchange tasks, you'll want the Exchange Management Shell. If you do launch the Windows Powershell, you can always add the EMS snap-in by running: add-mshsnapin *exchange*
Note that after Beta 2, this cmdlet will change to: add-pssnapin *exchange*
What version of Outlook are you running? If it is Outlook 2007, then Outlook will connect to the Client Access Server first as part of its Autodiscover process. Did you verify that the mailbox to which Outlook is connecting is located on the clustered mailbox server? Perhaps the mailbox was created on the standalone server and needs to be moved?
Also, for a great place to browse and ask more questions related to Exchange 2007, see http://forums.microsoft.com/TechNet/default.aspx?ForumGroupID=235&SiteID=17.