I initially thought that "Interested" was automatically generated based on post views or something similar but came to realization that it is not the case. The next conclusion is that it is human curated by a member of a Quantopian team.
I often find that I am more interested in posts in the newest category than those marked as interested. Curator's interest and mine obviously diverge. So maybe a better name would be simply 'Curated'.
ps. I said it before but Ill repeat - great job on the forum software