#4876 is indeed at IAH in new colors, unfortunately unable to get a pic.
I spotted this A319 tonight (8/22) around 20:15, just after her landing from AMA ferry flight UA2719 -- the first A319 to sport UA's new livery.
She was taxiing west in the darkness past Terminal D and the old C-North -- with the snappy new blue tail illuminated and all window shades open / interior lights on. Beautiful, but odd-looking -- odd due to the bright white light shining from the windows causing the new large U N I T E D titles to look a bit disjointed in that darkness.
I was driving in the same direction, so I followed N876UA until she docked in at C14. Nice to see up close. Don't know where this bird will fly tomorrow after her RON at IAH.
What happened next BLEW MY MIND --
About 20:35, N39297, a recently new-liveried 738, arrived at the next gate over, C15 -- this was UA1148 from LAX, full of pax.
It was absolutely bizarre and amazing to see these two -- an A319 and a B738 side by side in the new bright scheme -- parked at C14 and C15, gates which are in the very attractive and well-lit new UA C-North concourse. I thought, "This is what the future looks like."
The unlikely conjunction lasted less than 90 minutes, as N39297 departed around 10pm for ORD as UA1854, leaving N876UA lonely at C14.
Unfortunately, I couldn't take any photos, as I was busy working.....