GUNS: Glock 19 9mm 15rd - $478. w/ Free Shipping

Quote from bas200000 : appears to be Gen 3

Huh, that must be what the OP meant when he said "This is about the cheapest price I've seen for a Glock 19 Generation 3 pistol"

Quote from slearl : Is that a bad thing?

No, Glock is still manufacturing both the Gen 3 and Gen 4, I think they are still making more of the Gen 3s, or at least it seems that way since that's by far easier to find for sale. Now that Glock has worked out the kinks with the Gen 4, both are very good, like a lot of things, there are people on both sides that prefer one over the other.

The main change is in the recoil system. Then some other, mostly cosmetic, changes, different grip texture, interchangeable back-straps, and a bigger, reversible mag release button.

Pricewise, there's typically like a $30-40 price difference, the Gen 4 being higher. The OP's deal looks like a pretty good price to me.

Quote from DisturbedAle : Gen4 is still not available to the general public in many states... CA included

Ahh, the joys of the People's Republic of Kalifornia. Gen4 Glocks are not on the Certified Handgun Roster in CA and won't likely ever be, which is why you can't find them for sale. (unless you go through the hassle and expense of the single shot exemption).

Here's a link to the list in case you are interested - http://certguns.doj.ca.gov/safeguns_resp.asp.
Note if you search for Glock the following message appears - No Generation 4 Glock handguns have been approved as of: Tuesday, October 16, 2012