If you want to get these in time for Christmas, Goodrock's put up specific order-by dates:
USA orders - please order by 12/14/2007
Canadian orders - please order by 12/11/2007
International Orders - please order by 12/7/2007
These cut-off dates will likely be pushed back by 5-7 days, but the sooner you get it out of the way, the better.
The only new thing that's been added recently are a number of new Year Zero stickers and pins. There may be a couple Year Zero/Art is Resistance shirts coming down the line soon, but from what I understand, these are not available in the US yet:
As soon as we find these at respectable prices, we'll be sure to let you know, but they're not even on the official merch site yet.
On a semi-related note, if you ordered anything from Faction and have yet to receive your shirt or a refund, please visit this thread on Echoing the Sound and add your name to the list, as folks there are pursuing further action via Paypal.