In the "File->Preferences" menu item there is a box marked "Check for updates on startup"
My observation (with Linux arduino-0018 and -0019) is that if you uncheck that box, Arduino will no longer automatically phone home.
My further observation (guess, actually) is that if it accesses a file on the server that contains "0017" this "feature" is worthless as an update notifier, and the "feature" itself needs to be updated or deleted.
I mean, it certainly didn't notify me that there was an update available for my 0018 installation.
Maybe the checkbox should have a more honest legend that informs the users that they have an option to let developers track usage or some such thing.
Regards,
Dave