I have made a couple trips to Olympic Stadium on Saturday afternoons just to hang out and enjoy some relaxing time. There are all kinds of vendors around the "concourse" there, and you can get quite tasty ice cream for about $0.25...probably cheaper if you are Khmer.
This is the diving platform and pool.This is the regular Olympic swimming pool. You can swim for about $1.00, I think, but I haven't gone.
This is the stadium, which is just opposite the swimming pool. There was a soccer game going on last week, but often people will be running or walking around the track or around the seating areas.
I'm not sure who was playing, but there wasn't much of a crowd.