Tophat is rated cold hardy to zone 3 so it should be OK in your zone 7 without protection. If you get a bout of weather that concerns you just move it into the garage for a bit. Probably not necessary, but won't hurt.

Bringing it into the house would be a mistake as it is too warm and will break it's necessary dormancy.

If it gets below -40 F then put it in the garage else leave it outside.

I was wondering has your Top Hat Blueberry ever produced any berries, because I thought of buying a
Dwarf-Blueberry but didn't thick it would produce as much as a normal bush?

I'd like to know if lilgirl's Top Hat produced any berries, too. If you did, how much? I'd like to buy 1 or 2 plants for my little niece (she believes that blueberries will dry everyone's tears and is a cure-all for "ouchies") but we live in California (zone 9 or 10?).

Is there another blueberry plant that will do well in a container so they can take it with them if they move?

Can't get any answers from the nurseries.

Well you're asking the wrong nurseries! There are a few dwarf blueberries out there, and they make fine container plants; granted, a bigger container is better but these plants won't be getting 5+ feet like their big brothers and sisters. 'Top Hat' is obviously one of them, and I think one of the smallest, but the few I've grown for my mom ... well they just didn't impress me. We got a couple new varieties (new for us) at work yesterday, I'll check tomorrow, write down some names for ya and get back on here.