From 标准教程HSK4上 (page 88):
If I'm not mistaken, the 了 is the change-of-state 了. But this gives two possibilities:
- The change of state is B going from B's former location to 丽江.
- The change of state is B going from 丽江 to B's present location.
My impression is that since the 了 is not directly after 去 (completion 了), we can deduce B is still in 丽江, and maybe A and B are talking on the phone. However, 玩儿 is also a verb, so maybe 了 implies its completion (instead of 去).
Question: Does 听说你去丽江玩儿了 imply they are still in 丽江?