There’s a new feature(really new) in Gmail that Google doesn’t want us to know about, though they just have updated the “what’s new” page last night.
The new feature is called “Mute Thread”, or “Mute” for short.
If you subscribed to a mailing list, and you want to “Archive” the message, make it disappear from the Inbox. But it won’t, every time a new message comes in, the archived email will show up in your inbox again. This is when “Mute” comes in, by using the ‘m’ shortcut key, new messages added to the conversation bypass your inbox so that the conversation stays archived.
Links: http://www.bladam.com/main/entry/gmail-mute-m-key/
http://mail.google.com/support/bin/answer.py?answer=47787
http://googlified.com/2006new-feature-in-gmail-mute-thread/

Cool. Looks like Gmail is getting ready for the non-beta.

When 15 Giga Google, When?
answer:
23 December?

adam comments here on this feature..

http://blogoscoped.com/forum/75214.html#id75390

Cool feature..
thanks for the update Haochi!!

Very cool, i really wanted this feature. A button would also be nice, but this will do.