We are currently working on a more stable version 1.0 release. I don't have a date for you, but I would expect it to be on codeplex relatively soon. However we have already started using the current beta-release on wiki.episerver.com as well as internally.
Keep in mind, that WikiX is open source and provided AS IS - so no guarantees. However, since you have the source you'll be able to adjust it to your needs and change / disable that you don't find work satisfactory.
Do you know if it will be upgradable? That is if I install the 0.9 Beta, will it be upgradable to 1.0 or do I have to start all over again?
What else can you tell me about the integration with the EPiServer database? Is there any new tables created? Can I install WikiX on my EPiServer 5 R1 site or do my site have to be in a R2 state?
It will be possible to make a manual upgrade. But of course if you change a lot of the code to adjust to your site / functionality, you might have to redo those changes - or only do a partial upgrade. You might want to change the templates, but upgrade the assemblies - however no guarantees that it will work.
No new tables are created (yet - might be needed in v.1). WikiX requires 5 R2 (it uses Dynamic content heavily).
WikiX was presented on the 'EPiServer days'-event earlier this month and I was under the impression that it was ready for production use but the current release is marked '0.9 Beta Release'. Does anyone know if it is suitable for production use or if I should await the 1.0 release? If so, does anyone know when 1.0 will be available?