The old AllTalk Manager has been folded into the Simple Plugins project.
This so far is the only plugin that does not require the core to function.

(27/09/09): Version 1.3.0
-----------------------
+ Added support for custom events via .cfg file
+ Added join message to display current alltalk status
- Removed event cvars in lieu of .cfg file
! Fixed threshold setting overriding event setting
! Fixed non-attack/defend maps not calling setup_period_end event. This effectively means you can now have alltalk on during the setup round and not have it break if there is no setup round. (TF2 only)

Admins can now use the supplied config file to hook any event they want to change the alltalk setting.