In nuce

I was just reading about gnip (guh-nip) [An obvious word play on ping], and this seems to be a cool way to solve the problem of consumers (service consumers) having to poll for event updates from publishers, such as digg, plaxo etc. What these guys do is to act a web service proxy between data publishers and consumers, thus providing a standard API. gnip ‘pings’ the consumer, whenever new data is available. An on receiving a ‘ping’, the consumer can poll for the new data. This solves the problem of people continuously polling for data.

This seems to me, a rehash of the old style event driven mechanism, for large scale service oriented systems; working on multiple data formats, including REST, RSS, ATOM.

There are some really nice explanations of how gnip works here.
and some more stuff is available at
http://blog.gnipcentral.com/2008/07/01/the-what-of-gnip-changing-apis-from-pull-to-push/
http://blog.gnipcentral.com/2008/07/01/the-why-of-gnip-stop-building-what-everyone-else-is-building/
Cheers,
Laks

“A witty saying proves nothing.” – Voltaire