USB hub as travel charger?

Most USB hubs I know of are powered via the USB port on the host device rather than being something you plug into the wall. However I have seen, and successfully use, a USB charger that plugs into the 12V outlet (formerly known as the cigarette lighter) of a car. I would be surprised if somebody doesn’t make a similar device to plug into a wall socket.

If your hub has an AC adapter, it should be able to put out 5V, 0.5A per port. Most devices can charge from that (notable exceptions: Palm Touchstone and iPad). You should test at home.

There are loads of USB wall chargers that just plug into an outles and I’ve seen some with four ports.

That works for most devices, but not all. For instance, Motorola Droid™-series phones like more juice than a standard USB port puts out; a standard USB port maxes out at 500ma while Droid chargers put out 700–850ma,

So the best answer I think that can be given is, “it depends on what you are charging”.

Here are a few things on the market that should work for you:
chargepod
4 port