Timing is at the core of Twitter. How current is this? How new is this? What's going on right now?

A tweet's 140 characters take no time to read and little time to write. And tweets stay visible in the Twitter search results only until they're buried by newer tweets. So Twitter's recently announced "promoted tweets" as a way to beat the clock--and to be seen in a search engine that caters to the most impatient searchers on the planet.

But these are not ads. They're tweets--with one difference: A promoted tweet will stay out there as long as people are engaging with it, and only when they've stopped will it disappear.

Twitter has been very careful to fit its new advertising program with its carefully cultivated "users in charge" philosophy. So, unlike regular online advertising, where an algorithm decides whether or not an ad is relevant to the user's query, on Twitter, the users themselves give the yea or nay--by retweeting, replying, adding it to their favorites or otherwise responding to it.

Twitter's calling this approach "resonance" and it will develop its criteria as the new program rolls out.

How it works
A single promoted tweet will appear at the top of the search results for a particular keyword--just one per page. Right now you pay for 1,000 views, but as Twitter develops its resonance algorithm, this will change.

The advertiser reserves a keyword and sets a budget, then chooses a tweet to promote. It's just like a regular tweet, except it appears in the search results with shading behind it and a label underneath that says "Promoted by Twitter." The promoted tweet also goes out to anyone who follows the company.

If people interact with the promoted tweet, it stays up and keeps being seen in the search results. Once people ignore it, the advertiser goes on to the next tweet it wants to promote for the keyword, until the budget for that campaign is spent.

However, if an advertiser's promoted tweets are so lame that everybody ignores them, Twitter refunds the rest of the budget and lets some other company reserve the keyword. So you'd better know what you're doing.

Here are two examples from Best Buy, one of the Twitter advertising partners taking part in the rollout:

The top ad is a great example of how to inspire response. It's got a specific call to action with a link that will let them measure how effective the ad is, and it all comes wrapped up in a social responsibility message that readers will want to share.

The second is, well, more like an ad, and probably won't be as effective.

Why would you want to use promoted tweets?
5 million tweets per day: Twitter is phenomenally popular and its search function has taken off, so guaranteeing that you can be seen in Twitter search results--and stay there for a while--is huge. From what Twitter is saying this early in the game, these ads will probably also show up in the live Twitter streams in the Google and Bing results.

You're marketing to the 18-34-year-old demographic: According to a consumer cross-channel research study by the Art Technology Group, 42 percent of them are using Twitter and other social media to do product research and shopping. And they're passing on their recommendations to anybody who reads their posts. If these people make up your market, Twitter is an important tool for you.

You're already using Twitter effectively: If you've already got a lot of people following you and responding to your tweets, then this could work for you. You already have some data on what worked and what didn't, what got retweeted and what got ignored, so you'll have a better chance of coming up with a promotion that will resonate.

You can get an even better idea of your effectiveness on Twitter with social media analytics tools like Objective Marketer and Twitter Analyzer.

What does this mean now?
At the moment, you can't run any promoted tweets unless you're one of Twitter's hand-picked advertising partners in this venture, including giants like Sony Pictures, Virgin America, Starbucks and Best Buy.

But there is a way you can ride on the coattails of the big boys. They're taking part in a grand experiment, so they're using their best brains to come up with promoted tweets that will work in this brand-new model.

Search the company names in Twitter. Do it a few more times, starting over each time with a new search. You'll see the promoted tweets they're cycling through. For each one, analyze what they're doing to engage members. See what's working for them and what falls flat (the Retweets tally on the bottom right of the promoted tweet will give you a good idea).

Is there some way you can adapt what they're doing for your own audience, and for the keywords people use to find you? Try a few borrowed ideas and see if you can get some retweeting happening among your own followers.

Go to school on those big corporations and it won't cost you one advertising cent.