Lo folks,
The IESDP has recently been updated (19/09/04), so go read it, and download the new version:
http://iesdp.gibberlings3.net/
Updates include opcodes and scripting info. Also note that the effects listed on IESDP are now available as downloadable .dat files, direct from the IESDP as well.

On an unrelated note, each member of the GbG series now has a website:
BG1: http://www.mcwrench.com/?path=/ie/mods/gbg/bg1gbg
BG2: http://www.mcwrench.com/?path=/ie/mods/gbg/bg2gbg
IWD1: http://www.mcwrench.com/?path=/ie/mods/gbg/iwd1gbg
BG1Tutu: http://www.mcwrench.com/?path=/ie/mods/gbg/tutugbg
DLTCdemo: http://www.mcwrench.com/?path=/ie/mods/gbg/dltcdgbg

NB. IWD1GbG has recently been bumped to version 2 to fix an installation error.