[mikeyur]

It's a push notification platform for anything you can build it into. Load up your HN profile and there's a Notifo box to get notified when someone responds to your comment. Apps they put together like Push.ly to notify you when someone DMs/RTs/Mentions you on Twitter (note: they released this before twitter added the functionality to their apps).

My friend uses it on a site for his sales/signup process, when a transaction goes through he knows immediately.

One of the plugins I use the most is their Chrome to Notifo plugin for Google Chrome. If I'm on a page I can hit the button and it will push the page URL to my phone.

[vyrotek]

Interesting. Are sites such as http://pusherapp.com and other hosted comet/websocket/push services basically their competitors?

[PStamatiou]

Same space, different offering. If you want _mobile_ push notifications, you need a mobile app in the App Store/Android Market that can hook up to APNS/C2DM, et cetera. Notifo does that.