Ok, the new actress stepping in the shoes as the Doctor's newest companion is not an avocado, (although that would make for an interesting Castaway style series 7) but the girl holding it, Jenna-Louise Coleman. She was previously in the British TV series Emmerdale and Waterloo Road and had a small part in last years Captain America: The First Avenger. Her next big project before Doctor Who will be in Julian Fellow's (Downton Abbey) Titanic miniseries.
She'll make her debut in the Christmas special after current companions Amy and Rory, as Stephen Moffat puts it, heartbreakingly leave the Doctor. As River Song would say "spoilers," so if you want to find out what be involved in their exit, you can read it here.
As I hate to see companions leave, I'm excited with what the new one will bring to the series because I love the chemistry between companions. Although I'm hoping this companionship will be more friendship than romance. Fall can't come soon enough.
Also if your wondering why an avocado has to do with the cartoon above, watch this interview with Jenna-Louise: