Hi Babowa,
The answer is a yes and a no.
The iMessages side can only send to Apple iPhone (numbers) or an Apple iOS device (Apple ID) or to Macs that are using Messages and have registered and Apple ID with iMessages.
However there is a holdover from the iChat days.
This using an Phone Number as a Buddy Name using an AIM Account.
There are a couple of codicils to this.
1) The Mac must be set as if it in the Untied States.
2) The Phone must be in the United States AND on a carrier that supports the AIM SMS forwarding
(the Link also deals with setting it up so IMs go to your Phone).
You then add the Phone number to the AIM Buddy List as if it were a Buddy but with a leading +1 as in +121324567890
In versions up to iChat 5 setting the region in System Preferences > Language and Text (or just Language in yet earlier versions) allows you to see the SMS menu items in iChat (Buddies Menu mainly).
In iChat 6 and Messages the SMS items have disappeared although the function still exists.
It would seem logical that, like the iPhone, the Messages app would swap to sending SMS when the receiver is not an iOS 56 or greater iPhone but this does not happen.
Aside
Strangely both my iPhones have stopped being activated for iMessages.
I noticed first that my Mac's Message App was not listing the phone number of one.
When I went through the process of Activation it spun the cogwheel forever and then showed the phone Number greyed out (I can't select it as Send From).
I checked my other iPhone and had to re-activate that and it has been at "Waiting for Activation" for ages (At least 30 mins).
7:21 PM Monday; October 15, 2012
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