Zabbix 1.8.3. has been released recently, a long awaited update with bugfixes and new usefull functionality. I personally use Zabbix for a few years now and implemented the tool around several large organisations.

To get an overview of what is changed; have a look at http://www.zabbix.com/documentation/1.8/manual/about/what_s_new_1.8.3 or download the latest release here.