If you did not have 'the talk' at Thanksgiving, you might consider sharing your family's financial information over the Christmas holidays.
You don't have to be specific about dollars and cents, but Certified Fiancial Planner Dennis Hebert says it's a good thing to let relatives know what you have in terms of accounts, and assets, and where the important documents can be found. Absolute musts: a will, a living will, a healthcare proxy and a durable power of attorney. You also need divorce decrees, military discharge papers and other personal identifiers.
Hebert offers a document called Love Letter to My Family that will help you organize.