I would hesitate to say "merely" a cultural custom or such. Even if the practice doesn't have a literal application for us today there are often underlying principles that we need to be aware of.
For example, the head covering. Paul's point seems to have been to try and maintain a clear distinction between the roles and the the appearances of the men and women in the church congregation. The whole discussion appears to be predicated upon the activity of "praying," and thus is specific for those times.
Even if we have different cultural styles with regard to the way in which we carry this out, we should still strive to maintain a distinction and to emphasize the glory that is due God in our prayers and worship together.
Similarly with the issue of women "keeping silent." Though this is obviously the preferred approach

, more practical considerations require that we look at what was prompting Paul's counsel in this matter. Notice his emphasis is on "obedience" here rather than a direct concern for the volume of sound coming from the ladies.
The underlying principle then would be one of order and obedience first. This principle then would be reflected in the local customs related to who speaks when and in what tone of voice, etc.