A THEOS engineer, Suwan Vongvivatanakij, put together an excellent overview presentation for the CEOS Working Group on Information Systems and Services (WGISS) for their meeting last February. I haven't seen a lot of detailed information about the satellite on the web and thus far this is the most comprehensive info I've seen.
The satellite has panchromatic and multispectral modes, with a 2 meter resolution at nadir for panchromatic and 15 meters for the multispectral mode. For mapping, stereo applications will be supported since there are three (forward, nadir, reverse) look angles.
If you hail from Thailand (or can read Thai) you can see the THEOS program homepage here: http://theos.gistda.or.th/home.html