Now that "Old School" RuneScape has been released, some people were asking if it's OK to do the same between that and the current RuneScape. Mod Mark replies that it's more of a trust issue, and mentions nothing about real-world trading:
What is the official rule about trading gp for 07scape gp?
Mod Mark: Good question. There is no way for us to support cross-product trading. If you made a trade on one game in the assumption that you'd get a trade on a different game then you'd be relying on trust alone. There aren't any rules or guidelines on this matter. Its up to the individuals involved. (bolded for emphasis)
This begs the question: is inter-game trading allowed now? Or has Jagex gone soft on real-world trading as a whole?