Still seeing this
Hey, I'm on a brand-new, un-rooted, unmodified Galaxy Nexus, that was updated to OTA Jellybean yesterday. This is still broken for me. Looks like it should work but doesn't send the message, just stays on the Google now view with a big blank space. It won't let me post links (too new), but there's an issue over on Google Code Android space. Plus there's the bug that the auto-response texts (when a call is missed), won't send through GV either. Only Messaging. Lame Google. Why create GV with those features, if you're not going to integrate it all the way? They really need a setting that's "take over all SMS/MMS functionality" and if you turn it on, Messaging is effectively disabled, as all it does is handed off to GV.
It'll help if everyone stars and/or comments on these issues there, unfortunately I can't link to them, until I post like 8 more times.