My phone number for my Iphone 4s is associated with my Apple ID however, it does not show up in my IMessage preferences on my mac and thus all messages I send from iMessage are sent from my Apply ID email.
I have just noticed that your original Posts lists OS 10.8
and not OS X 10.8.2
Your phraseology in the last post made me look again.
Does you iMessage Account pane look like this ?
At OS X 10.8.2 Update the Messages App is updated to version 7.0.1
This changes the pic above (the Sign Out and Detail Buttons are no on the "Front" part)
The Send From Drop down has been added at the bottom. (You may only get this with Two active "Receive" names/iPhone Numbers)
It used to look like this
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.2)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images." No, Seriously