How should siblings share the burden of providing elder care for our parents?

Do you have a resource for information on how to discuss and plan for a parents care among siblings? My wife and I are close to Mom and my wife's siblings are younger with young children and career concerns impacted by the economy and we feel they are putting things "out of sight, out of mind" for convenience. How can we talk about the many issues in elder care amongst ourselves and with the aging parent? Are there certain steps to follow or stages to consider before bringing the parent into the questioning and planning process? We are closer to retirement and our children are already out of the house and on their own.

We feel a great deal of tension and we want to avoid the family being driven further apart.