A coffee shop and a laptop are convenient, even fun ways to produce mediocre content. A blog entry, email, maybe even cleaning up a few lines of code. But as most programmers know, sooner or later, you have to enter another mode to get that additional "oomph" to get the important critical-path work done. Some call it "the zone".
In fact we just talked about this the other day:
http://news.ycombinator.com/item?id=2450260
A coffee shop is probably the best way to think you've entered the zone without actually entering the zone. The can be very dangerous. You've had a good time surrounded by like minded people (kinda like being here at hn), but you've never actually transcended anything really important.
I spend time at the library one or more times per week, sometimes just to get out of the office. It's fun to think and get transactions done, but fortunately, I have an internal guide that tells me, "Time to get back to the silence, large screen, and comfortable chair of the office to get the real work done."
I realize that this isn't the same experience as others, but I still often want to ask them, "Did you really get done what you wanted to get done in the coffee shop?"
This subject reminds me of a great line from Joel Spolsky's "Hitting the High Notes":
http://www.joelonsoftware.com/articles/HighNotes.html
"Five Antonio Salieris won't produce Mozart's Requiem. Ever. Not if they work for 100 years."
My version:
"Five workers in the coffee shop won't produce the killer work that one in a dedicated space can produce. Ever. Not if they drink 100 lattes."