I got a problem with logging into a service a couple of weeks ago. I sent them mail, no answers. I wrote on their Facebook page a few days later (no harsh words). They called me home in a couple of hours and we fixed the problem on the spot. I wrote again on fb to thank them.

Going public means getting in front of people that care more about customers or has more time to do so. It feels a little like skipping the line though.

The difference here is that you attempted normal contact first, and waited for a reply. If everyone immediately defaulted to publicizing their problems with their relationships with companies, it would be both more annoying for everyone and less effective. The importance they place on your publicly aired problems is relative to how many of those problems they see and the expected negative impact. A thousand people complaining about your service daily will not receive the same attention and treatment as when there's a single person complaining.

It's just getting to the point where emailing a company through the normal support channels is just a joke. Their email queue is days long, while their Twitter queue is minutes.

What needs to happen, and probably has little chance of happening, is for people to always mention how understaffed the support at the company in question must be. These companies are under-staffing their support and it's contributing to the situation where things often need to be publicly escalated before they get the attention they need. Making support and customer service part of their reputation will go a long way towards solving that. There's really no excuse for support as atrocious as some companies have become known for. Sure, some of the products are free, but at the same time they are able to monetize the aggregate of all that free use, so there's really no excuse, since the free use and their revenues are intrinsically linked.

It makes them more likely to help you and less likely to do it happily. Depends on circumstances whether that is better for you.