Sandisk has announced their new 2GB MicroSD card - double the capacity of their former 1GB offering. While they are not the first 2GB MicroSD on the block, they are...err...the most Sandisk of current offerings. Look for them in Japan Oct. 25th. Sandisk's site acts like they might be available in the US as well (linking to local retailers).
I still don't have any devices that require MicroSD, so I've been saving money by purchasing larger formats. But I would probably sleep better at night if I started purchasing MicroSDs and using adapters - which is a lot more practical with 2GB available.