Hi,
on a weekly base the (draft) GRASS 5.1 programmer's manuals
are generated in PDF and HTML and stored here:
http://grass.itc.it/grass51/manuals/
(available on the mirrors the following day)
So far the Vector library and the DBMI are documented.
The other libraries should be subsequently 'doxygenized'
when they reach the 5.1 CVS.
Thanks to the Doxygen team,
Markus
PS: We need more developers to test GRASS 5.1 