Hi,
the first version will already be released next week!
But we also have already some plans for future versions, many of those we just came up with after a lot of discussion at the RCOMM 2010. One of the major goals for the next version will be to simplify the integration of own pieces of R code as a predefined operator within RapidMiner. Right now, you will have to use the generic "Execute R Script" operator or you will have to edit an XML description if you want something beside the already delivered R operators. That's fine, but in future versions it is likely that you can define the input and output ports including their pre- and postconditions as well as parameters in order to fully integrate complete self-written R operators with a few clicks only.
But for now we are already happy with the upcoming version

Cheers,
Ingo