Police drummer Stewart Copeland is known for his Sacred Grove jam sessions where he invites his musician friends over to his home studio to mess around on various instruments. Copeland's friend and fellow drummer Neil Peart has been involved in these sessions in the past, and Copeland just posted video of another recent session titled A Little More Noise involving Peart along with Danny Carey (Tool), Matt Stone (South Park) and Matt Scannell (Vertical Horizon). You can watch the video below or on Copeland's YouTube channel here. From the video's description:

Some new drums arrived so Peart and Carey came over to lay heavy hands upon them. Scannell and I banged out any old riffs while Stone chimed the gongs. Couple days later four MORE drummers dropped by and took up the horns. The piano was an afterthought. ...with Mike Dolbear, Thomas Lang, Dave Elich & Aaron Sterling.

Copeland also hosted a jam session with Peart, Carey and Les Claypool back in 2011. That track/video was titled Count Drumula! and featured all four guys trading off on drum duties along with Claypool on a stand-up bass and Carey playing a trombone. You can see a video from that session here. There was also a lost session at one point that involved Alex Lifeson and Peart as Copeland describes in this post.