I have no idea about why "arenawarriors" web site/forum disappeared from the net, if this is what you are searching for. I was never registered on their site, however noticed their forum was not very active since many months, before it disappeared.
I'm not inside OA clanscene/third party communities, so the fact I don't know about other Italian OA communities does not mean there are not.
However, people around this forum which are surely Italian are:
- Jackoverfull: he's not very active on the forum, but he's the one who compiled Mac OSX OA binaries, and can give some help with Mac problems... he kindly appeares if invoked with a PM.
- Akom74: Q3 mapper since a long time, he created 6 of the OACMP Volume 1 maps for OA.
- Gig (me): I try to help where I can, providing feedback and keeping an eye on OA wiki. I rarely play online.
There may be more Italian people around these forums... I can't remember now...