No matter how you configure the "caller ID" option, if a friend iMessages you (i.e. they initiate the convo) to your cell phone number and not email (most common, as if they were texting but it silently switched to iMessage), the message will only be received on your phone.
Apple needs to add an option to allow you to authenticate/verify your phone number as a valid receive address for the desktop ASAP.
Apple seriously needs to put some UX talent working on this.
I've assumed that most iMessage use thus far has been as a transparent transport for SMS over a data connection. Is this correct?