I get the lean startup "talk to customers first" thing, and it seems perfect for so many startups. However, I can't help feeling there are some cases where you are selling execution not innovation and therefore "show don't tell" is more important. In these cases customers already have an existing solution which they probably don't consider a pain point and you literally have to show how their lives could be better to convert.
Some off-the-cuff examples include Facebook, Google Search and Google Chrome (unlike Google Maps which could have been a lean startup), Xero, the iPod and iPhone, nearly all media/entertainment.
I still think "release early" and MVPs are essential to avoid investing more effort than you have to in order to test a hypothesis. Likewise, I still think that getting in touch with your target market early is important as well (you're going to have to reach them at some point, so better start early to make sure they actually exist). But I question whether conversion potential can be evaluated for a pain point your customers don't realise exists until they see the alternative.