social media cosSocial media is becoming a tough game to call for research companies. Several recent reports present divergent looks at ad spending projections and the potential size of key players, all pointing to the possibility that spending in this area is more spontaneous than search, display, or even traditional media.

Take, for example, two reports issued today on ad spending projections. The first, from eMarketer, predicts $2.3 billion in worldwide on social network advertising in 2009. In 2013, spending will reach an estimated $3.5 billion. Those numbers are positive on the surface, but they represent a 50 percent reduction from eMarketer’s last projection, delivered in December 2008. The company, which culled research from Deloitte and comScore for its projections, says the limiting factor is the worldwide economic crisis.

Or is it? Forrester Research social media analyst Jeremiah Owyang released a report Thursday that shows more than half of interactive marketers surveyed (53 percent) expected social media budgets to increase as a direct result of the weakened economy. The reason for continued growth, says Forrester, is the weak economy. The reason it will not grow as fast as thought, says eMarketer, is the weak economy.

The problem in handicapping this race lies in the size of the overall budgets and the agility with which social media campaigns can be executed. Three-quarters of marketers report that their social media spend is $100,000 or less over 12 months, according to Forrester. Some 45 percent  said those budgets were not set during year-to-year planning, but were determined “as needed.” Only 26 percent based the budget on last year’s spend. Seven percent said they didn’t have a budget. The increase will pick up pace this year, according to Owyang because they can be “deployed quickly and inexpensively in a recession. These messages have the potential to move rapidly through word-of-mouth and can deliver measurable results. But the data also suggests that marketing through social media remains in the experimental phase.”

Another research debate is growing in the potential size of Facebook. Ross Sandler of RBC told Silicon Alley Insider today that at its current growth rate, Facebook will surpass Google in size by 2011-2012. Sandler assumes a “modest deceleration in growth” for both sites (an 85 percent increase in unique users for Facebook and 20 percent for Google).

The growth rate becomes the tough number to call. Marketers need to look at a sustainable growth range in this area, which has reset all expectations for usage. Example: according to comScore, in February of 2009, Facebook received 36.03 percent of all U.S. social network traffic — an increase of 149 percent from its 14.46 percent total one year earlier. Compare that to MySpace, which dropped 28 percent in the same timespan, falling from 72.92 percent in February of ’08 to 52.21 percent in 2009.

Who could have called that a year ago?