Changes since Asterisk 1.4-beta was branched:

  * Argument support for Gosub application
  * MailboxExists converted to dialplan function
  * Ability to set process limits without restarting Asterisk
  * SS7 support in chan_zap (via libss7 library)
  * Proper codec support in chan_skinny.
  * AEL upgraded to use the Gosub with Arguments instead
     of Macro application, to hopefully reduce the problems
     seen with the artificially low stack ceiling that 
     Macro bumps into. Macros can only call other Macros
     to a depth of 7. Tests run using gosub, show depths
     limited only by virtual memory. A small test demonstrated
     recursive call depths of 100,000 without problems.