i want to send a wedding card to Prince William & Katherine Middleton.. To what address do I send it?

You can send a congratulatory wedding card to the Royal couple at Clarence House, London SW1A 1BA. Prince William and Miss Middleton ask that anyone who wishes to give them a wedding gift consider giving instead to a charitable fund. Donations can be made through the website www.royalweddingcharityfund.org.

Sunday, February 05 2012
Source: http://www.royal.gov.uk/Contactus/Contact%20a%20member%20of%20the%20Royal%20Family.aspx