From the article: Firewall fire sale: Free ZoneAlarm makes it to Vista

The Vista version of ZoneAlarm, a two-way firewall that will continue to be given away, is the first from a major security vendor to apply Vista's Windows Filtering Platform (WFP) API, said Laura Yecies, the general manager of Check Point's consumer security line.

It enables an outbound firewall (The firewall in Vista also supports this, it just happens to be hidden in the Advanced Firewall MMC). I'm not a big fan of outbound firewalls as:

  1. The software is already on your machine. ( if(!PingServer()){Delete("*");} )
  2. It could probably send it through another enabled app (use the web browser, hide it in a ping packet)