Disabled the old plugin (2.0.2), uploaded the new one, enabled it. It says it needs to connect to WordPress. I disable W3TC, click connect, and it says:
Jetpack could not contact WordPress.com: register_http_request_failed. This usually means something is incorrectly configured on your web host. Operation timed out after 15007 milliseconds with 0 bytes received
So I disable, upload the old 2.0.2, re-enable, and I can't connect with the old version either. So now it just plain doesn't work.
I've installed the Jetpack Compatibility Test, and the HTTP/HTTPS connection tests are coming back as 200/OK. Any ideas?