As of an hour ago, comments on WikiTree profiles generate e-mail messages to the Profile Manager(s). This is much like how it works here on G2G. Before this, the only alert that you'd get when a comment was posted on one of your profiles was the one in your Activity Feed. Many WikiTreers wouldn't see these until they got their weekly Activity Feed update by e-mail on the following Wednesday morning.
I'm hesitant to add features that generate e-mail messages because of the danger of abuse by spammers and the sensitivity related to it. I think this was a good improvement but please let us know -- either here or via e-mail to info@ -- if you see any abuse or any bugs or problems.
P.S. You don't currently have the ability to opt-out of these e-mail updates. To stop getting any kind of WikiTree e-mail you need to cancel your membership. However, we'll be adding a feature in the next couple weeks that lets you opt-out of e-mailed comments and/or the weekly Activity Feed updates.