UPDATE: It's a new album and a live show...sort of.
ABBA are getting ready to announce something at what they're calling a "historic livestream" today (9/2) at 12:45 PM Eastern. The livestream was announced last week via a verified Twitter account, ABBA Voyage, and ahead of it there are billboards in major cities around the world this morning, featuring the band in TRON-looking outfits, with the tagline "The future of ABBA begins today." (See billboards in London below.) As to what "Voyage" is -- an album? a tour? both? something else? -- that remains to be seen, but you can watch via ABBA's YouTube channel below.
Having broken up in 1982, Agnetha Fältskog, Björn Ulvaeus, Benny Andersson, and Anni-Frid Lyngstad officially reunited as ABBA in 2018, after playing together at a private party in Stockholm in 2016. A new song, "I Still Have Faith in You," aired as part of a TV special in 2019.