"Engagement Ads", a new internet marketing strategy appearing on Facebook has come in for a bit of criticism.

The ads work by letting Facebook members leave comments on participating adverts, add the brands to their fan pages and use them to send "virtual gifts" to friends.

While your friends may then give you virtual thanks for your virtual generosity, the importance for Facebook, according to blogger Caroline McCarthy, is that it allows the company to experiment in ways of surviving on advert revenue.

And of course for advertisers themselves, this is the perfect way to expose their brand to the people using these sites.

However, Ms McCarthy believes that "engagement ads won't be the magical cure, because it simply won't work for most advertisers".

She continues: "Rather, it's a niche option that will probably lead to very successful campaigns for some brands - and high-profile blunders for others."

The problem is that little-known companies will find it difficult to get users to begin interacting with their adverts, and some of the interaction may involve criticism.

She cites the example of a 2006 promotion by General Motors, where the company let users produce their own video adverts, but environmentalists quickly turned it into a campaign on global warming.

So are Facebook barking up the wrong virtual tree with engagement ads or could there be a future for them?

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