IEGD 10.2 drivers are working fine on Poulsbo US15W (graphics device ID 8108) with Linux 2.6.31 and Xorg 1.6, but it looks like it is lacking support for Poulsbo US15L (graphics device ID 8109), which is used on some MID devices.
It looks straightforward to add support in the open-source kernel part of IEGD, but the Xorg driver is proprietary and can't be modified.
Does Intel plan to introduce US15L support in IEGD drivers?
The Intel Embedded Graphics Drivers supports embedded products from the Embedded and Communications Group. The US15L is a product that is not on the ECG roadmap as it is supported by the MID guys (Ultra Mobile Group).
The US15W and US15L are very similar and I agree adding it would be fairly straight forward (and make the US15L 'better" in Linux), however it just is not planned at this time.