Hello,
Milestones are an often requested feature. Although we plan to integrate Milestones into AceProject eventually, we unfortunately cannot give you an estimated time of arrival for that. Meanwhile, you might like to try the following work-around solution for Milestones:
1) Create a Task Type called "Milestones"
2) Create tasks of this type, with 0 estimated hours and a start and end date on the same day.
Best regards,