Revenue hasn't been as fast to change as end-user sentiment, but all that looks like it's coming to an end next year. Social networking site Facebook, which passed 350 million users last month, is poised to move ahead of rival MySpace in ad revenue in 2010, according to a report from eMarketer. The research firm expects Facebook to rake in $605 million in ad spend next year, compared to $385 million for MySpace, which is a News Corp. (NWS) property.

According to Debra Aho Williamson, senior analyst at eMarketer and author of Social Network Ad Spending: 2010 Outlook, "As more marketers incorporate social networks in their business, they will no longer look at them as siloed destinations. Instead, they will look to increase the impact of their social network presence by linking it to other marketing initiatives, both online and offline."

A new executive team is trying to bring MySpace back to its former glory. By focusing on music, videos and games, it hopes to recapture some of its luster. With the MySpace refugees mounting, it's time for some new blood to make some brilliant, future-changing decisions. This week, the company is holding a conference for its global ad sales team to explore ways to bring in traffic and beef up ad spending.

MySpace is poised to haul in $495 million in ad revenue this year, down 15% from last year's $585 million, according to research firm eMarketer. In August, MySpace attracted 64.2 million unique visitors from the United States, off 15% from August 2008, according to comScore, while Facebook pulled in 92.2 million unique U.S. visitors – up more than 100% year-over-year.

The general sentiment is that online advertising is immune from the travails of the economy (obviously, this ignores the depression for the category in the wake of the dot-com bust). The argument is that the consumers' "eyeballs" are moving more to Web-based media.

No doubt, this is true. But, this doesn't mean advertisers won't still get skittish.

As a result, eMarketer is toning down its forecast for online ad spending in 2008. Instead of coming to $27.5 billion, the revised figure is now $25.8 billion.

OK, that doesn't sound like much. However, it could be brutal for many companies (especially small ones that rely heavily on ad spending).

Oh, and social networking sites may come under pressure too. Simply put, these sites are having a tough time getting people to click on ads (even though there are many "eyeballs").

Something else: eMarketer's revision shows how fragile the economy has become. In other words, things can certainly get worse -- and quickly.

Tom Taulli is the author of various books, including The Complete M&A Handbook and The Edgar Online Guide to Decoding Financial Statements. He also operates DealProfiles.com.

With a $15 billion valuation for Facebook, it seems that social networking is destined for huge monetization opportunities. Yet, a variety of venture capitalists have expressed some skepticism lately. Basically, it's not easy advertising to the social networking crowd (as seen with Facebook's Beacon initiative).

This week, eMarketer published a study that forecasts that social networking advertising is expected to reach $4 billion by 2011 (on a global basis).

Keep in mind, though, that research firms don't have clear-cut crystal balls. It's not uncommon for them to get too aggressive on these estimates. Also, in the realm of the frothy Internet, the $4 billion figure does seem a bit muted -- especially in light of some of the recent valuations.

Something else: eMarketer thinks that about half of all online adults will be on social networks by 2011. Really?

I can certainly understand that teens will remain avid. But, adults have other things to do besides social networking (such as making a living, taking care of kids, and so on). In other words, if eMarketer is counting on adults for social networking riches, it might want to think again.

Tom Taulli is the author of various books, including The Complete M&A Handbook and The Edgar Online Guide to Decoding Financial Statements. He also operates DealProfiles.com.