The venerable Cycles, Blender's powerhouse physically-based path tracer, celebrates its 10th anniversary this Friday! The Blender Foundation is organizing a live stream on Friday the 23rd at 5 pm CEST to celebrate, featuring Cycles creator Brecht van Lommel and frequent Cycles contributor Sergey Sharybin.
— Blender (@Blender) April 19, 2021
The tweet also hints at a special announcement, with the stream page already present on youtube being simply titled "X". See you there in a few days for the event!
On a mail to the Blender Foundation's committers mailing list, Ton Roosendaal reminisces about Brecht's "Modernizing shading and rendering" blog post announcing Cycles on the 23rd of April 2011, which turned out to be a watershed moment in Blender's storied history.