Gwen Stefani and Gavin Rossdale arrived in Cannes with Kingston and Zuma today. The family of four hopped onto a small boat that took them to a luxurious yacht owned by Russian businessman Roman Abramovich, and later they were spotted on dry land enjoying the sights of the French Riviera. Gwen and her boys made their way south from London, where they spent the last week visiting parks and meeting with pals like Gwyneth Paltrow. Gwen's at the Cannes Film Festival on behalf of one of the official partners, L'Oreal, which has also welcomed other ambassadors Diane Kruger and Aishwarya Rai Bachchan. Diane wore a sexy black outfit to a bash sponsored by the brand last night, and we'll be watching out for Gwen's glamorous debut as the festival rolls on.