I see a very big difference between an Amazon.com wish list and a registry.
A registry is connected to a particular event: traditionally a wedding, now also new (especially first) baby, which are events for which people traditionally needed equipment for a very different stage of life -- unlike other gift-giving occasions like graduations, bar/bat mitzvah, birthdays, Christmas, etc.
A wish list on a site like Amazon.com is just there all the time, whenever someone wants to know if there's something you've been longing for. It doesn't disappear after a set period of time like a registry usually does. If someone buys an item on it for you, it's still there, I believe, unlike a registry, which is managed by the store or site. If someone ever wants to buy you a gift, for whatever reason, they can see what you would like.
And, as magicdomino says, people do use them as shopping lists for themselves, too -- even though Amazon.com now does have separate lists for wish and shopping -- which I found out the hard way when I thought I had bought the perfect gift for a friend, because I bought it off her amazon.com wish list, only to have her say, "This is exactly the one I already have!" when she opened it (not very politely, eh?
) She had bought it for herself or perhaps received it as a gift from someone else and forgot to remove it from her list.
A wish list does not indicate that you are thinking that people will be buying you gifts for any particular occasion. A registry does.
So a "housewarming registry" suggests that you are expecting people will buy you substantial gifts for your new home. And although many people do buy housewarming gifts, they tend to be small items like plants or coasters, except perhaps from very close friends and family, who don't usually use a registry to know your needs and tastes -- they just ask you or surprise you.