Taylor Swift and Joe Jonas are never ever getting back together -- but they're most definitely on much friendlier terms these days!

Backstage at the iHeartRadio concert in Las Vegas Sept. 22, Swift (now dating Connor Kennedy) was psyched to catch up with her ex, 23, who infamously dumped her via a 27-second phone call back in 2008.

According to an observer, Swift "hugged and kissed" her currently-single ex at the show, and had a friendly heart-to-heart. Things were less cheery between Jonas and another ex, Demi Lovato. Get the details on their icy encounter in this week's Hot Stuff video, as told by Us Weekly's Senior Editor Ian Drew -- plus special guests, comedy legends Vicki Lawrence and Tim Conway!

Also in the roundup? More on Rob and Kristen's reconciliation, Mila Kunis tries Kabbalah with Ashton Kutcher, and more.

Watch the clip now!