waldoappPanelists rarely talk about what they say they’re going to talk about. Sessions meant to be about the hardware revolution evolve into a discussion of Kickstarter’s merits, a pow-wow about which hot-button startup might go public next becomes a call to avoid going public at pretty much any cost, and Google can be called out during a panel it’s hosting. You’ll almost never get what you (probably didn’t) pay for, and that’s okay, because these deviations from the conference schedule are often more important than the original programming anyway.

That was the case at an Application Developers Alliance-hosted event ostensibly covering app discoverability last night, where executives from Millennial Media, Appboy, AppStori, Samsung, and Applico were meant to teach developers how to get their photo-sharing, social networking, or casual gaming apps noticed in a sea of similar software! attract users.

And, to be fair, there were a few tips for getting an application noticed. Make a press kit. (Please, please, do this.) Reach out to blogs. Try to get people talking about your application. But these tidbits largely served as segues into more pressing issues facing developers, from keeping the users they already have to ensuring that they are working on the right product.

“Something sometimes thought about in a secondary matter is retention,” said AppStori’s Arie Abecassis as he introduced the panel. “While this whole session is about discoverability, it’s worth keeping that in mind, because I think that’s some of the latent challenge developers face.”

The turn towards retention wasn’t unexpected, as Appboy, whose chief executive Mark Ghermezian spoke on the panel, was founded on the idea that developers need tools that help them keep users. It’s also directly related to the other problems developers face, with each member of the panel reminding developers to focus on their products and start out with a business model in mind. That doesn’t work if people don’t use — and talk about — an app.

“A small percentage of apps get used, and an even smaller percentage get used a lot,” said Louis Simeonidis, Applico’s chief marketing officer. And he’s right: Onavo reported in February that less than half of the people who download an app use it more than once. Whether or not that’s a problem for consumers is up for debate — I’ve argued that it isn’t, more than once — but it’s certainly a problem for developers, who need to keep their users engaged with their product.

It was Millennial Media’s director of global monetization solutions, Glen Nigel Straub, who “closed the loop” between retention, quality, discoverability, and business. “You can’t think about how to make money [after an app has launched],” Straub said, “Because you might be using money to acquire users.”

There’s the rub. Despite the panel’s intentions, and a few, mostly-obvious tips from the Application Developers Alliance and Abecassis, app discoverability isn’t something developers can truly “crack.” They’re at the mercy of the platform makers, whether it’s Apple, Google, Microsoft, or BlackBerry, and, short of paying for downloads (which Apple isn’t particularly fond of) there’s no discoverability hack that will lead to overnight riches.

Which is why the most important thing said about app discoverability all night was uttered in an elevator heading down to the building lobby. “There is no trick here,” an attendee said. “And if there is, nobody’s going to be going on stage and talking to us about it.”