I have existing websites with PHP/MySQL framework. They are very busy and chat, events, vs (interval) ajax implementations added to server load as well. Now websites are going bigger so I need to change to long polling/comet but apache is not very well with these and most of the comet servers are done in Java. Like cometd, www.stream-hub.com, activemq.
Are there any server implementations that I can use without re-coding the ajax pages in java or least coding in Java/Python.
You may want to take a lookg at Ajax Push Engine its a push engine that works well alongside apache. The server portio is written in C so you dont need to worry about running a java or python server.
Also you may want to investigate the new HTML 5 web socket specification. Web Sockets will allow for direct socket programing in javascript, which often removes the need for long polling/comet. Keep in mind that HTML 5 hasn't been fully embraced yet by all browsers tho.
You could try a SaaS comet solution, such as WebSync On-Demand. There's no need to recode much, you can just subscribe in your page, and publish from your server to that subscriber. Since it's a SaaS solution, it works great with PHP - there's even a pre-built PHP library for exactly what you're trying to do.