I got it recently as well. However it seems that the message always go through. You can assess that by going into your google voice account (www.google.com/voice), in the Texts folder you see the message has been sent. I think the timeout error comes from Google Voice server and it resends the message automatically.
I just started to receive the Read Timed out error as well. I am using an IM to send a text to a group of people. The first person on the list always gets the message but no one else receives it. Could google voice have changed its auto text detection system?