Last night, I put in IMAP over SSL for the first time. It was surprisingly easy.
More or less, it went like this:
Open up port 993 on the firewall to your Exchange server.
Make sure the IMAP service is set to automatic.
Then go to the Properties of the IMAP virtual server:
ESM -> Servername -> Protocols -> IMAP4 -> Default IMAP Virtual Server
Go to the Access tab
Hit Certificate -> Assign existing certificate -> and then you choose your SSL certificate (same one you have for OWA)
Then you need to turn off regular IMAP by requiring secured connections. Go to the properties of the Default IMAP Virtual Server and click on the Access tab. Click on Communication. Check the box for Require Secure Channel.
And really that was it. Then I was able to connect to IMAP over SSL. Of course client configurations are necessary, but that's relatively easy.