BBC Radio 4 broadcast Catherine Tate interviewing David Tennant on Thursday. It’s very good and very funny and available from a link on the right hand side of this page until Thursday 28th February.
Spoilers ahead, I guess:
This was recorded a couple of days before Catherine signed the contract for her character Donna’s appearance in Series 4. It is clear from the interview that the pair of them have an amazingly good rapport. Catherine’s ignorance about Star Wars, and David’s rant about astrology are particular highlights.
I’ll be available to help any US Who fans who bother to listen with any cultural issues - some of it is very Brit-centric. 
Here’s a starter - The Bill.
