multi-chip module. It sounds like they're taking a bunch of KGD (known good die), wiring bonding them together (most likely) or flip chip on top of a BGA, and then encapsulating it all. It's not a complete SoC.
Right now, the highest single chip integration I can think of is everything on a PC (x86 CPU, MMU, display controller, IDE controller, etc) minus the memory.
In general, it doesn't seem cost-effective to integrate large amounts of DRAM memory on-chip (note that chips with large on-board caches such as the Intel Xeons use SRAM and are also quite expensive). IIRC, it's because the optimum process needs of logic (CPU, etc) and memory are somewhat different.
For a semi-affordable single chip (<$100), the memory king is probably Motorola's embedded PowerPC MPC565, with something like 26K SRAM and 1M flash, or a DSP from TI or ADI; some of them have ~1M SRAM, no flash, and $100-$200 price tag.
IIRC, there are a couple graphics chips with large amounts on on-board DRAM (e.g. Neographics did one, Nintendo GameCube), but these haven't been run-away successes.
Tony