Besides the post from my good friend, Aung OO, on Exchange Provisioning using ILM 2007 and FIM 2010, one thing to keep in mind is that if you don't get the Exchange 2010 RPS URI correct, then you might get weird errors when exporting even though you don't expect to provision any mailboxes. Twice now (thus the blog post) I've been hit by the following error, in two different environments:
The WinRM client received an HTTP status code of 502 from the remote WS-Management service. For more information, see the about_Remote_Troubleshooting Help topic.
In my case, I hadn't actually flubbed the Exchange 2010 RPS URI, it was logically correct, but in this particular environment it needed an FQDN, so instead of http://exchsvr/powershell I needed http://exchsvr.mycompany.com/powershell.