Asychronous server alternatives

Hello all. Im currently in the process (revising the database to be specific) of creating a site that will inlude persistant chat functionality, and I had a couple of questions I hope you guys can help me with: 1. Which comet server do you guys recommend to combine with django (or perhaps pylons, Im still undecided between the two), or would you recommend a more custom approach with twisted? Scalability is my main concern. 2. I plan on using apache as the http server, django (or pylons) as the front end, with postgres for the database. I haven't decided on a search solution; but as far as perfomance is concerned what would you recommend I consider incorporating? (such as a reddis cache) 3. Is anyone using jython-Django? I really wanted to use this combination since I also have a background with Java; however it seemed too new.