There is a helpful discussion on beliefnet.com about the Revised Common Lectionary. This includes a comment from Taylor Burton-Edwards, the secretary of The Consultation on Common Texts which did the work on this lectionary. Two points are worth highlighting:
1) A lectionary “is a selection of readings intended to be read, sung, heard, and proclaimed over a period of time in the context of Christian worship as Christian worship has been practiced in the “catholic” or “ecumenical” church.” Some think that Sunday worship is or should be a Bible study class. Sunday worship does not replace personal and group Bible study and prayerful lectio divina, it complements it.
2) A lectionary builds on the great lectionary traditions that we have inherited – all the way back to our Jewish roots.
The current discussion on beliefnet
A previous discussion on beliefnet
The Consultation on Common Texts website
My book Celebrating Eucharist on the readings (Chapter 7)