Prosper LogoAlthough the service is only a few years old, Twitter marketing is nothing new. First there was Ashton Kutcher‘s race to a million followers. Nothing in it for the followers, but boy did the media swoon. Copyblogger gave away an iPod Nano, SmartyPig gave away $100 to people who could answer their Twitter questions, and Zappos gave free shoes to whoever would re-write their (self-admittedly) boring customer service messages.

Now P2P lending service Prosper, fresh off their site relaunch in mid-July, is hosting a Twitter contest to grab more followers and, ostensibly, more attention (worked on me, anyway). Prosper is giving away $500 total, $25 to 20 different Twitter users who friend @prosperloans and tweet the following message:

$500 for 500 followers! Follow @prosperloans and RT to enter to win 1 of 20 $25 GCs http://bit.ly/GBUkR #prosper500

The contest runs from Monday, August 3rd to Friday, August 7th at midnight. You can check Prosper‘s progress on the #prosper500 hashtag. Since the contest kicked off 17 hours ago, it has generated 15 tweets. Which on a per-tweet basis is costing Prosper about $6.67  (assuming we’re one day into the contest, or $100, divided by 15 tweets).

Do these contests work? And what are they worth? Prosper isn’t just selling shoes, or trying to attract blog readers. They’re making loans, and word of mouth can only get you so far… on Prosper, you need a credit score of 640 or higher to get a loan, and you need some serious cash to be a lender. Is the Twitter generation really the one to target here?

SmartyPig follower count for Jul 3 - Aug 3, 2009Some metrics from SmartyPig’s recent $100 giveaway might be helpful. SmartyPig is an online service that helps consumers save money for big events through a series of financial and social tools. On the day of their contest, SmartyPig grew by 51 followers (+1.2%). In the ensuing seven days, their follower count stayed flat, and a week later, actually dropped by 37 followers. Compare those results to the impact of a mention in a New York Times article on July 2nd, which yielded 79 followers (+2.0%) on the day of the article, and arguably netted 170 followers (+4.4%) over the three-day weekend. Further, follower growth continued on an upward trend after the article.

Prosper hasn’t had an article in the New York Times since their faux relaunch in April, so maybe the $500 would be better-spent on a plane ticket to New York and some climbing equipment. Now that’s publicity!

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