Bruno Senna DID Test with Mercedes DTM this week, nothing offical has been released on times or anything but reports have said that he was very strong during the practise and its a good sign for him getting into one of last years Mercedes cars for this DTM season.
Bruno looks set to do both DTM and the Le Mans 24 hour this year in preperation for an opening in F1 with help from Mercedes. Mercedes now give engines to back markers Force India, so if an opening is available there, there is always a chance 2010 will see a Senna in there.
Remember none of this is 'offical' as Mercedes have a very strong, don't talk about anything offically until we say so policy and theres still 2 months till DTM starts. But the signs look promising at least.