I can confirm this:
Using ZCS Import Wizard for Outlook from Windows SERVER produces error "Unable to logon to profile", regardless of Outlook profiles or MAPI installed on server.
So I copied all .PST files (which I created with EXMERGE) from server to one of client Windows XP machines, and I was able to use ZCS Import Wizard to copy all PST's to coresponding Zimbra accounts without problems.
...oh, yes, and if you want to import also messages in size over 10 MB, which is default top limit, add the following registry key on client XP computer, on which import/export procedure is running:
and enter size in MB in HEX notation (for example, enter 1E for 30 MB limit)