Hi All
after a couple of false starts with other versions I am running ICS 4.0.4 on my i9000T (Telecom) using this rom following instructions from here

http://www.theandroidsoul.com/android-4-0-4-rom-galaxy-s/

 Plus l am using "Modem_UGKC1_ICS.CM.I9000" from this site 

http://perka.zapto.org/
 
search for samsung then i9000 then ICS CM Modems then 850 in box on lower left hand side of screen

also it all has to be installed using CWM after Back up etc 

one thing I have found DON'T let contacts sinc with Google or else you get duplicate entry's

am using Go Dialer  for t9 dialing & contacts etc. plus Go SMS as I like it, also trying out the Nova launcher as seems to work well with ICS

so far all going well hope it stays that way

Pete