In preparation for the Developer Chat later today, Jane Wells posted an explanation of the purpose of these chats on the WordPress development blog.

From the post:

It’s understandable that many people want a direct line to the lead developers, and knowing they will be in a specific place at a specific time makes it easy to corner them to pitch pet requests, but please respect that these busy individuals are continually prioritizing the pet requests of hundreds of people and millions of users. Hijacking their product team meeting doesn’t help anyone’s cause.

Dev chats are held every Thursday at 20:30 UTC on the freenote IRC network in the #wordpress-dev channel. Chats typically last one hour, and the next chat is later today.