I am using Invensense gyros in my project. The gyro includes an internal digital motion processor. The new Invensense devices will include gyro and accelerometer internal.
The problem with the Invensense devices is that their DMP block is proprietary and closed. My particular project does not fit into their mold, and since there is no direct access to their logic, I cannot use it. Are there other manufacturers that are or will be including such capabilities inside of a 3 or 6 axis device? Currently I think Invensense is the only one, but it would be great if some other options become available.
I am unaware of any such competitive devices, but I wouldn't doubt one of our manufacturers is working on this.
I know it is not a gyro/accelerometer part, but ST's new device the LSM303 has a accelerometer/magnetometer. I found it quite interesting because they've helped ease some of the difficulties with using a magnetometer. It's not in stock yet at the chip level, but the in stock iNEMO sensor board does include the LSM303 as well as gyros and other sensors. The iNEMO isn't quite what you are looking for, but it's the only other platform that I know of that offers some freedom to develop the functionality that you desire without starting from scratch. I'm sure others might be able to chime in on the subject.