One of the clips featured an alien very similar to the one seen in "Greeks Bearing Gifts" (you know the one - the lesbian, Mary). During the short preview, Sarah-Jane Smith is seen talking to the creature, as young Maria - her neighbour - watches on in astonishment.
It would seem that, like the "Cyberwoman", the BBC Wales production team are attempting a sort of inter-series link. From what I've heard, this is not so much a crossover, as much as a 'special appearence'. I don't believe the alien plays any other part in the SJA episode.
But there's only one way to be absolutely sure, isn't there...?
The Sarah Jane Adventures airs on Monday January 1st at 4:25pm on BBC One. You can keep up with all the latest news by visiting Torchwood.TV's sister site, Sarah-jane.tv, here.
If I was cynical, I'd say this entire post has been one long advertisement for my new blog...
Lucky thing I'm not then, isn't it?