Public support and help forums have been around for quite some time. Based on the concept that two heads think better than one and that 1000 are even smarter, lots of open source or low profit organizations have relied on forums as their primary support source. The obvious advantage to this is: its cheap. But there are others and plenty of other advantages.
First there's the advantage of looking at problems from different (countless) perspectives. Some issues have a unique solution, others might have multiple ways to be solved. People might come up with solutions that even designers or creators didn't think about.
Then there's feedback. You can post a question and you'll get replies (or direction to previous replies to the same subject) really quickly (if you have a broad enough user base).
Another positive aspect is that it could be a really good source for inspiration and ideas for improvements. You could hear from the "source" what things don't work as expected, what things might need changes or adjustments and what things users want to see coming out (as a matter of fact I've read quite some posts asking for the next generation of ThinkPad tablets, just to quote an example). Then it'd be up to decision makers to evaluate if what they've learnt is where they want to go.
Finally, if all the data is well ordered, moderated and recollected it could eventually build up a knowledge base, the source of FAQ and answers for call centers and eventually cut (in part) support centers. If you find good answers on a website-forum you won't ever dial that 1-800 number.