This bug is a WontFix in GNOME Bugzilla
so I am proposing an Ubuntu only fix. In my oppinion, that would be in full accordance with Ubuntu phylosophy.
"Should be able to use all software regardless of disability."
I strongly feel that a strong urge to cycle tabs with Ctrl+Tab is in GNOME enviroment indeed a disability. That disability was imposed on users by some very popular apps -- namely FireFox -- that have spoiled their good taste in the field of keyboard shortcuts.
Because GNOME in Ubuntu indees comes bundeled with Firefox and it is promoted to Ubuntu users, Ubuntu should therefore bear the consequences for the impedement brought upon FF users and relieve them in other applications, i.e. Empathy, for a start by implementing the same Ctrl+Tab behavior.
This is a bug on which Ißve proposed the patch on the first time: