Actually, my wife came to me a few weeks ago and asked if I thought she should have her head covered during worship.  I was immediately humbled and thankful for her genuine desire to be obedient to God.  We bagan to look at this topic and began to evaluate the scripture and some trusted commentary (I tend to go to Grudem and Calvin first).  I thought Josh's sermon (heard via Podcast) was also helpful and we came away agreeing that head coverings are not necesarry for women but that proper cultural symbolism and behavior indicating her condition as a married women was necesarry.  More importantly, her purposeful appearance and behavior as a married Christian women are necesarry.  It is with great caution that I would say that a particular command of scripture is only appropriate to a particular historical or cultural context (I won't attend a church with women as pastors, for example), but there are times when that is true and I think this is one of them.  The underlying purpose of God's command must be considered along with the command.