In the brief time that I've been watching the Erlang world, I've noticed several cases of people saying:
The only example I have handy is Russell King's post on Jan 22, where he says, "For whatever reason, google search didn't give me anything."
In my experience, when a search on an obviously-distinctive term fails to yield an obviously-canonical website, the problem is usually that the website is poorly search-engine optimized.
Years ago, I worked at HotJobs.com. When I started, if you went to Google and typed "hotjobs", the results showed our homepage, our discussion boards... and nothing else. Why? Because the most valuable part of our website – the job listings – was not accessible by clicking links. Google couldn't crawl our most-valuable content, and thus it didn't appear in Google.
We eventually, collectively, came to our senses and fixed this bug. Shortly thereafter, we started getting a lot more traffic courtesy of Google, and everyone wondered why we hadn't done this sooner.
I suspect that something similar may be true for the Erlang HTML documentation. It's not hidden behind a search form, but it may be poorly browsable by a web crawler: frames are involved, links seem deeply-nested, possibly lacking helpful keywords. Long documents also tend to be penalized by search engines. Maybe something else is amiss.
Consider for a moment the PHP documentation, which has one page per function call. Choppy, but quickly browsable, with short and descriptive URLs. Search for "print_r" on Google and you get the PHP manual as result #1.
Searching for a similarly-obvious keyword in Erlang yields strange results. "io:format" returns www.erlang.org/doc/man/io.html as the top result, but "erlang io:format" drops it to 2nd place. Wierd!
That's as far as I've investigated. Google's Webmaster Guidelines are a good starting point for further investigation...