I just pushed a fix to master and 4.7 which fixes the memory leak in the filewatch service. The root of it was the same as in the file indexer service: no event loop in the work thread means DBus events piling up without ever being garbage collected.
Well, that is fixed now and the filewatch service will not steal all your memory anymore.
http://trueg.wordpress.com/2011/10/24/memory-leaks-in-nepomuk-nah/
Ввиду отсутствия event loop'а сообщения DBus накапливались и жрали память. История успеха, чо :}