When I'm planning a release, or planning on who to assign what to, I often want to gather a subset of features to look more closely at. It gets easy to loose track of features when the list gets long. I could use a tag to collect a set of features, but I don't want to pollute the global tag space. Usually these sets are fairly short-lived and private, but I can imagine cases where they are shared across a team, too.
|Release time frame|
As you mentioned, Tags is one way that this can be done. You could also leverage custom fields or other criteria to help better filter the views and information you are looking for.
Based on the available workarounds, we will mark this idea as already exists.