I haven't actually tried one of those but I was interested
also so I asked about them on the PIC microcontroller list as an
off-topic message.  I got two replies from people who have them and,
from what I received, my advice is to not get too excited.

        The tip is a two-piece device with a gap between the two
poles.  The solder or the work one is soldering is supposed to short
out the space between the two poles where the heat forms between the
work or solder and the tip.  One guy told me that the gap is about a
tenth of an inch such that it wouldn't be good for soldering
electronic components on a circuit board.

        In other words, they work but only in certain types of
situations.  I was hoping to replace my Wahl cordless soldering irons
which work fine, but use nicads that have to be replaced every few
years when they get to where they won't hold a charge.

        The other drawback to the new soldering tool is that you might
accidentally introduce 6 volts in to the circuit if one got one pole
of the tip against some part of that circuit and the other pole
against some other part instead of creating the short as desired.
That is more than enough voltage to fry most IC's if misapplied so all
in all, I was glad to have been told all these things.  The soldering
tool doesn't cost much, but if it isn't going to work for the purpose
I would have bought it for, it is a waste of money.

Bob Martin writes:
>Has anyone had experience with Radio Shack's quick cooling soldering iron?