I know some options using ruby on rails and/or node.js and PubNuB, a service that has many APIs so you can send/receive notifications between (almost) any platform.
I now how to send messages from PHP and how to receive them there using Amazon SNS, but how can I receive a push notification (a SNS message) on a JS/jQuery script?
Thanks.
Yes, but not directly and you'll have to poll for messages on a timer...
In the Product Details page under the heading "Flexible", you'll see that none of the currently supported formats/transports can be hosted in the browser.
However... Amazon SQS is one of the supported transports, and it in turn can be accessed from JavaScript - see an example app here: http://aws.amazon.com/code/Amazon-SQS/1254. (The example shows JavaScript accessing SQS).
You'd have to manually poll though, as there is no "push" to the browser with SQS.
(Alternatively, you could do it all server-side, and then you could use potentially use websockets to push the messages to the browser.)