I'm so sad for you and your cat and hope you will reunited soon, but I must say it's ironic that I just read an article about a pet detective! Although you may not go to this extreme, there are some good tips on finding lost pets at www.goodnewsforpets.com/Articles.asp?ID=910.
I love my house cats, but I was glad to read that a south china tiger, who was thought to be "functionally extinct, was spotted in the wild! What a lucky person to get this picture!