This is a "Clone Wars"-esque animated serial of three-minute epsiodes, broadcast weekly as part of the "Totally Doctor Who" children's companion programme to the main show. As previously mentioned in another thread, it's a 13-part story with the Doctor and Martha (voiced by the actors), and apparently a space pirate played by Anthony Stewart Head.
The first episode has now aired (and I'll leave it to you to find it yourselves). As kiddy cartooney things go, it's not bad, even if it feels very rushed, far more so than the "Scream of the Shalka" serial from '04. It's got the usual Doctor Who feel to it, with Tennant's animated persona chewing the scenery as usual. Martha isn't given much to do here, probably because the animators hadn't been given much on the character at the time, so she's left saying things like "Wow, Doctor! That's amazing!". Hopefully subsequent episodes will fix this.