Who said social media was cheap? Social media marketing has often been thought of as a much cheaper way to reach consumers than traditional advertising. But that’s not necessarily true, especially when it comes to Twitter.

In a recent interview, Twitter’s director of revenue Adam Bain told ClickZ that the cost of the company’s in-house advertising offering Promoted Trends currently costs $120,000 per day for advertisers, a steep increase from the $25,000 to $30,000 the popular microblogging site charged for Promoted Trends in April 2010. Meanwhile, its Promoted Accounts and Promoted Tweets products are auction-based, but require advertising firms to spend a minimum of $15,000 over three months.

Google believes that its new +1 feature, the search giant’s equivalent to Facebook’s Like button, will drive more qualified traffic to advertisers’ websites and could increase the overall click through rate (CTR) as +1 annotations increase over time, reports ClickZ.

The feature, which enables users to click to recommend search results and ads, will only be available to users that are signed into their Google account. Vice president of media strategy at Klick Communications Julie Batten outlines what the new feature means for advertisers:

1) What Does This Mean for Organic Rankings?
Google believes the +1 button will help them provide more relevant results to its users, and plans to use the information derived from the feature to help optimize its organic rankings. “Clearly,” notes Batten, “the amount that your site is “+1′d” could potentially have a significant impact on your search rankings.”

2) So How Do Sites Get “+1′d”?
Advertisers need to do three things: optimize their sponsored search user experience as much as possible, for example, being able to deliver on a query that someone searches for both within your ad copy and the landing page you drive to. Make sure that content is relevant and compelling—that visitors will recommend it to their friends. Finally, try to make your offering stand out from the competition and maximize positive customer experiences.

3) How Trackable Are +1s?
No reporting is currently available, though Google promises this will soon be available within an advertisers Google AdWords account under the Dimensions tab.

So what’s the end result? It looks Google’s +1 will be another tool in the social bookmarking arsenal. But will it become a a key weapon, or an also-ran to Facebook’s omnipresent Like button? Watch this space.