Howling noise in 1st gear?
 

While coasting in 1st gear slowly today, I heard a slight howling noise. I'm not sure where it was coming from but when I clutched in, it went away. This is not the normal "transmission whine" that we hear from all Boxsters. Anyone have any ideas? The car still drove normal after.

The first thing I would do is check or change the gear oil.

Gear oil was changed about 5k ago. Is there an easier way to check the level besides undoing the fill plug?

Not that I know of.

So I looked under the car and it appears that the transmission oil is leaking. I suspect it is very low. What are the chances that damage has been done? The car drove home fine in exception to the howling noise pulling out of the parking lot.

That gearbox is pretty expensive, I would not be driving the car until you can have someone competent look at it...........

+1 JFP in PA
1st and 2nd gear on the lower shaft are part of the drive shaft in the gear box and the
others float. If you leaked enough fluid to run these dry they will likely whine as any friction will transfer through the shaft. (The floating gears usually dont transfer noise as much)
I would check my tranny fluid before driving it any further, if you top it up and the noise is gone you might have caught it in time.
H