Which is the front in a zero setback seatpost?
 

Does it matter?

Eh, unless you've got something significantly different from what I've seen, there should only be one way that it can sit that you'll be able to get the saddle level. Also, there are generally some measurement markings on the rear of the seatpost...

Yes because because the place where you mount the saddle onto the seatpost will most likely be angled. If you have the seatpost backwards, your saddle probably won't be able to get level and will be tilted down a lot.

If there's writing on the side, align it so the writing reads properly. Usually that's a good way of doing it.

Applies to front hubs too, unless there's a one sided cone locknut or something that differentiates left and right sides of a front hub. And, no, it doesn't matter from a technical point of view for a front hub.

cdr

Thomson labels the seatpost (Front).

If you put it the wrong way tilting will be backwards rather than forward