Well, I have to post again just to let everyone know that I'm a happy iPhone 4S user again!
I got to think that my iPhone was damaged, but it was a software issue and misconfigurations.
At the beginning my iPhone was draining at a 10%/h rate, I managed to improve that by configuring it correctly (turning off some services and going easy on notifications and location services) and it improved to 5%/h.
It was still not a good result so I started to research at this forum, and I installed 9A406 and restored from a "optimized configurations backup", but it didnt help at all.
As a final steep what I did was a full factory reset and no restore from previous backup, and kept the iphone with no apps installed (and no mail, nothing at all, just like a new factory OTB iPhone) for a day ... Battery started behaving as promised, 0,5%/h!!!! and the other issue I had with battery not getting fully charged was also gone (my battery was charging to 70% max!) so hardware issue was out of the table. thanks to sbailey4 who gave me many advices on how to improve battery life.
Now I've been enjoying a 1%/h since yesterday, with 3 e-mail account fetching every 30 mins, 3 or 4 calls of 5 mins aprox, no whatsapp, MSN Messenger online 24/7, and optimized settings for notifications and location services (please refer to previous posts to identify this settings).
As a conclusion I must say: Restoring backups was causing me this issue, there´s something wrong with the process of backup restoration, something in the background gets misconfigured (I don't know what exactly) so please don't do it until a new iOS build comes out. Just configure your phone manually, I know this is a PIA, but is the only thing that worked for me.
Just install 5.0.1 and after that do a settings reset (in my case I had to do a full reset, proceed as you wish).
My iPhone was 100% charged yesteday's morning at 11am, right now (8:40am of the next day) my battery is at 75%! It works!
Thanks again to sbailey4!.
Greetings.