This is more a topic for the Dev forum, or maybe the Contributors group, when you'll have something to contribute/test, and if you'll be willing to contribute Btw, what other plugins have you created? Were they released publicly?

If you won't get the answer soon, i suggest you to try to contact Gato via private message or email.

Re: Tigase. I don't see this as being as offering as many plugin features as Openfire. Is that true? What benefit would this provide?

Re: Clustering. So far I'm up for volunteering for the effort, and don't think it's that hard (famous last words) to get the basic model functional. I just don't want to be the only one spending my hours developing it. There was some talk about the Igniterealtime Openfire road map showing making clustering easier to install,  e.g. listed under "Version 3.6.x, Q2 2008 - Q3 2008". Thinking that they were somehow opening this up, it made sense to wait. I'm not so plugged in with the dev scene, maybe someone who is can comment?