Hi Paulo !
First of all, I would like to tell you that you are doing a great job on SP and that I particularly liked your moutain pages. As we are both sharing the same interrest for some places in the Andes and as I plan to climb some of "your" moutains, your comments/images/videos interrested me a lot !
Concerning the "prohibition" to climb some mountains in Chile (such as San Pablo, San Pedro, etc.), I would like to say that... it is not prohibited to go to these summits ! As a matter of fact, unless you are chilean, if you want to get there, you have to get an authorisation from the official DIFROL administration (Dirección Nacional de Fronteras y Límites del Estado). These authorisations concern almost every high chilean mountain located on the border of this country. If you don't have it and if you are "caught" by chilean police in these places, you are normally breaking the chilean law.
Obtaining as many permits as you want from DIFROL is simple and free, though it takes a bit of time and must be thus thought in advance. You can do this through this web sites (in spanish and in english for some parts) : http://www.difrol.cl/index.php?option=com_content&task=section&id=12&Itemid=27
Of course, even if you have your valid DIFROL permit, chilean police will sometimes strongly recommend you not to go to certain mountains (such as Llullaillaco) because of mine fields or other objective dangers (potential volcano eruption can be one of them). But it would only be a warning as you legally have the right to go for it if you have your permit from DIFROL.
As you and many climbers did, it happened to me to climb chilean mountains located on the country's border without having the DIFROL permit... Some of these places are so remote that being spotted by police seems to be simply impossible !... but it is better to know that it is officially forbidden. Therefore, I could easily imagine that one would have some trouble in case of accident in such places (no insurance coverage for example).
Kind regards and hope you'll keep up enjoying climbing in the Andes and share your experiences !
Thank you Guillaume, I`ll add that info to the mountain page.
Cheers and many thanks