Well SAS only has the Q400 version as far as I remember. Q = Quiet I think and the 100, 200, 300, 400 is the size as you probably know but the Dash-8 Q400 seems to be the fleet model. Quantas has had theirs checked and cleared by a small norwegian airline found corrosion in the hydralics or something like that which has to do with the landing gear. Doesn't sound good.
Frank
According to Wikipedia (I know, bad, it's not a real good source); the grounding only applies to 60 aircraft, all of them being Q400s. This means it's not a generic Dash 8 issue. The Q is an emphasis on the aircraft that have the NVS, basically an ANR setup for the entire aircraft.
I haven't heard anything about a cause at this point.
Note that it seems in the industry 100-300 aircraft are all called "Dash 8s" while the Q400s are specifically called "Q400s."
That said, I'd like to note that Wikipedia lists them all as "Dash 8s" so I wasn't quite correct in assuming the Q400 was flat out considered a different type.