From the change log:
# Patched security flaw in iaxclient
# Patched md5 to work on amd64 (Jasmin Buchert)
# Added Malay translation (Mohd Effendi Jaafar)
* Updated Bulgarian, French, Polish, Spanish, German, Italian translations
* Fixed possible crash on systray click
* Fixed accidental dialing on group collapse
* Fixed DTMF from keyboard - invalid keys are filtered
* Cleaner disconnect (unregister all reigstered accounts)
* Contacts are now grouped in account folders
* New iaxclient with tipix Echo Cancellation
* Added support for Italian, Spanish and Hebrew languages
* While calling just press number keys to send DTMF (no need to switch to dialpad)
* Call register shows call duration
* Added icons for registration status tracking
* Added options for muting incoming and outgoing rings
* Added option to run command on incoming call
* Fixed bugs.
In the process of the development of Asterisk a new protocol has gathered
the attention among the VoIP users - the Inter-Asterisk eXchange, or IAX
(TM), Protocol, used as a the native communication protocol between
Asterisk PBX Servers. What is particularly good in it is that it requires
only one UDP port per endpoint to create a successful communication channel
for VoIP calls. This makes it much friendlier for users behind NAT, which
is not the case with SIP and H.323 - they required specific router
configurations for their channel establishment, thus hindering faster
spread of VoIP on the home and corporate desktop.