Now that there's word that Google will release GrandCentral 2.0 a friend comments that they should implement SMS messages to work with your GrandCentral number.
I heartily agree.
If I know Google (and this will prove if I do or not) they will do this and more. I've been dreaming of this for many moons:
Gmail Contacts will be integrated with Gmail, Gmail Chat and Grand Central. Gmail already has SMS capability and I dream that it will all come together to truly become the last phone number I'll ever need.