i have pinned a build some days ago. now this build is no longer visible under the activity tab. that would be ok. i can access it at least using the history tab. in a few days, the pinned build is no longer on the first page of this tab, too as build count increases. now i have to search for it by walking through the pages or entering a tag (well, i don't have defined one in this case).
so i think it would be helpful to have a "Pinned" tab next to the history tab, showing all pinned builds. maybe you can extend this for tagged builds, too (not required in my case because you can search for them and they are not that important in my use case). the tab could then have the name "Marked" or something else.
another option would be introducing another section in the history tab as on the activity tab called "Pinned Builds" showing the last 10 pinned builds. well, i would prefer solution number one because the pinned builds may grow during the lifetime of a configuration i don't want to search for them using tags or walking through all builds in history.
just my 2 cent.