I tried out a couple of Nordic Semiconductors nRF24L01 modules using maniacbug‘s RF24 Arduino library.
They work fine and cost next to nothing.
They could be used as a replacement for the RFM12B, although reports of the death of the RFM12B may have been exaggerated.
I have no immediate plans to use the nRF24L01 modules, but will wait and see what sort of infrastructure the open source hardware community builds using these modules.
What I would really like to do is to to work out how to communicate with my Coulisse blinds that use 2.4Ghz transceivers.
Geek Grandad 
Hi,
A bit late, but I wondered if you ever figured out how to remote control your coulisse blinds with 2.4GHz transceivers?
I am looking into doing this too, but I have no experience with arduino/raspberry pi whatsoever, so if there is anything you have to get started, that would be great!
No, I never did investigate it. It looked hard to make any progress and I don’t find that I use the remote function much anyway.