Disclosing your websites

I've talked with a few people about this, and opinions vary. While some have absolutely no problems with disclosing what websites they own, some restrain from doing that.

What is you opinion on this? What are the pros, and what are the cons of disclosing the websites you own (and all other information)?

May be some one would not like to disclose their off line sites.

G!

I have always wondered what the cons would be in doing this. Maybe they are afraid of having their sites copied or something similar.