Gaim! Any desktop Linux users from 20+ years ago likely remember the Gaim instant messaging app that was commonly shipped by desktop Linux distributions for interfacing with different instant messaging platforms like AIM, MSN, ICQ, etc. About twenty years ago Gaim was renamed to Pidgin though due to the AOL Instant Messenger trademark. But with the AIM trademark since expired and wanting to take a differing approach from the latest Pidgin, Gaim 3 is under development...
After KDBUS failed to make it into the mainline Linux kernel more than one decade ago as an in-kernel version of D-Bus, BUS1 was proposed as a clean sheet design for in-kernel, capability-based inter-process communication (IPC). BUS1 didn't gain enough traction to make it to the mainline kernel and then many of the same developers devised Dbus-Broker as a more performant D-Bus user-space implementation. Well, as a big surprise now, a new version of BUS1 is being worked on for the Linux kernel...