It's possible that the dying of gear to represent teams (red/blue) isn't final. One would assume they would do what they did in GW1 and make the cape/tabard/guild reference what denotes what team you're on. However, either way, I don't think you will be able to turn it off.
---------- Post added 2012-02-01 at 04:54 AM ----------
I think the shield is a mesmer ability. Look at the last two screencaps on that GWinsider post. You can see the Charr Mesmer (the notation under the screencap confirms it) next to a team member (What looks like a Norn Engineer) who doesn't have the shield. The Guardian party support ability places the shield on all nearby party members, so if it was the guardian ability it would be on the engineer as well. Also... it is CLEARLY purple and not because of an eye trick with the red armor.