Many use their blogs as a way to gauge public opinion. I for one, think it's a great use of technology. And I have to admit, I do occassionally dabble in the opinion gathering myself. ideeli.comblog (a great on-line sample sale site) wants to know your opinion of pop-up shops and fur!
Now, I like the idea of pop-up shops, although I think they are mostly found in NYC. I have yet to hear about any in the Boston area. Pop-up shops also are a great idea for budding designers and boutique owners. You don't have to commit to a long-term lease and you can do some "street testing" of your products. I'd say they are a win win. (now we just need to move the phenomenon across those state borders...)