sadly after playing with some plugins it seemed that somehow a bit of potentially malicious code entered the blog. It was appended on all themese footer.php and i'm currently trying to investigate (and asking the wordpress guys over at WordPress-Support) which plugin it was and how it injected the code.
Upon a quick analysis of the code it seemed that no harm was done - it connected to a site transmitting no data whatsoever. !So it didn't actually harm anything! (as far as i could see...).
The matter is now resolved, and even the google Malicious-Code-Check doesn't raise a alarm anymore ...
Sorry for any inconvenience caused!