Noam-
Maybe it would be helpful for me to take some screen shots of my GV set up and let you (or others) see what all check boxes, etc, I have checked?
Here is what I am doing...
1. I log into my GV account using browser.
2. I go to my Inbox.
3. I click the red "Text" button in upper-left.
4. I enter my GV phone # as the recipient.
5. I click Send and in my Inbox, I see only one text appear.
6. On the Text2x10 console, I see ONE text come in, and an X10 command gets sent that in turns my lamp.
7. Again, for me, it only does it once.
If I also use my iPhone to send a text to my GV phone #, again, I only see one text come into Text2x10 and get processed (and only one will show up in the GV inbox).
Heck, maybe I'm just lucky...