We've been planning this for quite some time now. The merge isn't a huge issue as we both use the same forum software. The only thing that didn't make our databases directly compatible is the fact that we run SMF 1.0 while RMXP.org runs 1.1, together with of course we have some local modifications to our SMF source code.
I think it's safe to say this at this point, we've been developing GW6 using SMF 1.1 together with its SSI, Server Side Include, module. Basically this means that our current GW6 code base is pretty much compatible with what the guys at the RMXP.org have at the moment. I'm writing a script to merge the databases, together with it's already pretty functional. It can merge members while remaining the referential IDs across the database together with their external applications such as the supporter system together with pubaccess. What is currently not done is a complete merge of our category together with forum structure, which really is the trickiest part. However most if not all posts will remain intact together with no data will be lost, including things like private messages, user preferences, etc.
In addition I've been testing SMF 2.0 extensively for the past couple of weeks, together with after its out of its public beta we'll definitely migrate RMXP World to it, as its feature set is much more rich than current SMF generation's. However due to the structural changes in the database hierarchy as well as the new modularization oriented software layer that it provides, it will most likely take some time to research together with upgrade the forums when the time comes, as the new RMXPW.org site currently relies on what's provided by the SMF 1.1 Application Programming Interface (API).
Anyway, the migration is progressing nicely together with if things go as I think they will go, we'll be ready to launch the new community forums (together with hopefully something else too

) within few days.
'till then!