8:14 p.m.: Following her opening performance, Swift swigs a bottle of water and gushes to her four-piece horn section, "You guys were amazing!"
8:31 p.m.: "I've never seen such a well-dressed audience. You're certainly more well-dressed than we are!" Coldplay's Chris Martin, clad in a humble white tee, jokes to the corporate crowd in the middle of the band's set, right before they play the Ghost Stories track "Ink."
8:45 p.m.: PepsiCo Beverages global CMO/consumer engagement Frank Cooper, the architect of Pepsi's recent deals with Beyonce and iTunes Radio is in the building (Pepsi is a festival sponsor), and is being ushered backstage to meet Alicia Keys by her new co-manager Ron Laffitte. However, with minutes until her surprise showtime, Keys is nowhere to be found for the time being.
9:00 p.m.: After slaying "Super Bass" and fan favorite "Beez In The Trap," Nicki Minaj runs into technical difficulties during her ferocious verse on Beyonce's "Flawless" remix. "iHeartRadio, do we have a problem?" Minaj says, before quickly clarifying, "no, I don't mean you, I mean [the sound guys] in the back." Seizing an opportunity to turn an audio gaffe into a triumph, Minaj decides to rock the rest of her "Flawless" verse a capella (surprise! It kills.)
The familiar snare beat to "Bang Bang" kicks in, and Minaj has to quickly glance over to make it clear that she won't be tackling this one alone. Within seconds, Ariana Grande appears, in a black miniskirt and black cat ears, with a melodic hammer to nail each and every high note of the Jessie J collaboration (Jessie herself was touring in Europe this weekend.)
9:21 p.m.: "I can't really dance, so I'm hoping enough of you know this next song so you can help me," Bastille frontman Dan Smith says, before the band rips into its dual cover of Snap!'s "Rhythm Is A Dancer" and Corona's "Rhythm Of The Night," retitled simply "Of The Night."
9:54 p.m.: Will.i.am is the first of two guests on hand to preview new tracks from Aoki's forthcoming album Neon Future I (out Sept. 30.) Their collaborative song "Born To Get Wild" follows in the expected footsteps of Will.i.am's other similarly themed party tracks for the Black Eyed Peas ("turnin' up the sound / cuz we make it crazy / we burning down the town / burn it down / so that everyone come around gets wild" is a typical couplet.) Will.i.am also gets to partake in Aoki's ritualistic cake toss.
10:12 p.m.: With 13 theater and club dates just announced in August, Jason Derulo's DJ made a pretty aggressive pitch to the iHeart crowd. "The greatest show on earth -- Talk Dirty Tour! October! Get those tickets now!" he boomed, moments before Derulo came onstage to twerk to his summer top 10 "Wiggle."
10:20 p.m.: Big Machine label boss Scott Borchetta tells Billboard that Swift's 1989 may not be the only pure-pop release on the label for very long. As part of a 2013 deal with hitmaker Dr. Luke, Borchetta has already identified another artist, male singer-songwriter Fancy, as the next potential pop-crossover breakout for 2015. Further aiding the effort: Scooter Braun has signed on for management.
11:32 p.m.: Since Usher begins his performance in the middle of the VIP audience, the camera captured many famous fans behind him snapping photos. One of the excited culprits: Glee star Darren Criss.
11:35 p.m.: Though Usher's set relied heavily on old hits ("OMG," "You Make Me Wanna," "DJ Got Us Fallin In Love Again"), he made his intentions for his new music very clear. "Alright, now there's songs I have that are classics, and then there's songs like this next one that have a classic sound for the new era." And then he ran through a brass-drenched disco-funk version of current single "She Came To Give It To You," even though guest rapper Nicki Minaj was no longer on hand to drop her guest verse.
11:57 p.m.: Derulo isn't the only artist who can't resist a quick tour plug: Usher teased of his soon-to-launch UR Experience Tour, "I can't promise it will be a nude show and I'll come out there naked, but I can promise you will have something special, specifically, specially for people like this audience here in Vegas."
12:00 a.m. "I'd like to introduce this young man that I've gotten to know," Usher says. "He's a friend, he's a brother, he's a passionate artist and I have a fortunate opportunity to have shared a song with him." Putting rumors to rest, Chris Brown emerges to perform his latest X single "New Flame" alongside Usher, and the results are appropriately both incendiary and torch-passing -- or, in the case of Usher, torch-sharing. The duet concludes with a mini-dance off between the two performers, with Usher intent on getting the final applause by dancing himself out of his high-tops and setting them on fire (peep the "New Flame" puns.)
12:13 a.m. Following his night-ending performance, Usher stopped to meet a fan in a wheelchair as soon as he got off the stage -- as in, he was still dabbing the sweat off with a towel.