So basically they are looking for hardware to fit open source Nokia N810 platform that is available from http://maemo.org/
From the responses at the initial post and the project site (see below) this might be something to look at. Yes I am happy with my Nokia N810 but if there is a tablet with larger screen like my IBM X61, I will jump. Heck at $200 I will join the project!
If you want to contribute, the project is here. Due to large number of comments, now the comments are here.