The rules of Pinyin are clear and easy - but only to foreigners.
Does anyone know:
- is there an authoritative norm (like GB..., YY...), which sets the rules.
- Pinyin is recognized by the UN, is there even an international standard (like ISO ...)
- any authoritative webpage that clearly states what is right and what is wrong?

Ôì·´ÓÐÀí - Zaofan you li - Rebellion is Justified

...should give you what you're looking for. That's how "foreigners" learn pinyin. (By "foreigners," I assume you mean non-Chinese.)

They all speak english in China but they just dont admit it to your face.

I believe pinyin was created by the PRC government. It's extremely standardized, and as there aren't really any new developments in standard Mandarin, there's no need for regulation-- it doesn't change. I believe it is also recognized by the ISO.
Sorry I can't be more authoritative, but if you find out more please keep us posted. (I'm a pinyin fan.)

We are vain and we are blind/ I hate people when they're not polite

Hanyu Pinyin was adopted by the National People's Congress on February 11, 1958 and you'll probably find the text of the formal adoption somewhere in a Chinese bookstore, if not on the web. It's sometimes an appendix to language textbooks.

There are many summaries of the formal adoption in English on the web and this one at a Harvard site is as good as any: http://icg.harvard.edu/~pinyin . You want the Pinyin Tables and note in particular the Supplementary Rules. They explain why it's Hanyu Pinyin, not Hanyü Pinyin.

Of course, the difficulty with Pinyin today isn't determining the Pinyin of a character, any Chinese dictionary will provide that, it's knowing how to string the Pinyin together. Is it Chang An Da Jie, Changan Dajie, Chang'An Dajie, Chang-an Dajie or what? It's surprisingly difficult to set up a consistent scheme for this and the formal rules adopted by China aren't very helpful. The Library of Congress has put a lot of effort into creating some rules and a look at their site shows a bit of the complexity involved. http://lcweb.loc.gov/catdir/pinyin/romcover.html and http://www.loc.gov/catdir/pinyin/pinyin.html .

There is, of course, an authority that tells you whether your pinyin is right or wrong. It's me.

find me at qiaoying teahouse, dongdaqiao lu (metro yonganli)

Yup, that would be true!

cheers from Ruth in Panyu