Project is marked as 'dead' on the website.
Re: Polling is very important
Most NMS's done persist a connection to the central server, so you can't check for a 'failed connection'. Additionally, most event managers don't have a comprehensive list of all host sending them events so they don't know to look for non-events.
The traffic behavior of your application helps decide if polling or sniffing is appropriate. Nobody wants to get up at 2:00am to respond to an alarm that there is no traffic to a host, only to find that the reason is it is Christmas Eve and nobody happens to want to visit the site. Ideally the lack of traffic would kick off a poll to perform an independant check.
Also, there is a difference between 'Event Management' and 'Network Monitoring'. EM is more along the lines of passive, someone-sends-in-alerts, while NM is more of the check-and-verify-it-is-working.