You can easily display recent and popular forum posts on your iD homepage  using RSS news. Add the following URLs when creating a News category as an RSS feed and place these in your iD CMS page.

Hot Topics:

http://<intranet url>/feeds/forum/hottopics.aspx?sid={subsiteid}&idactorid=loggedinuser

Latest Posts:

http://<intranet url>/feeds/forum/newtopics.aspx?sid={subsiteid}&idactorid=loggedinuser