Facebook may have a long way to go in proving that it can monetize its rapidly growing mobile audience, but with its IPO just days away, the company is making it clear that it has plenty of options for generating revenue.

Case in point: the world’s largest social network is experimenting with a “Highlight” option that allows users to pay for a status update that may be more widely distributed and seen for a longer period of time.

TechCrunch’s Josh Constine explains:

Highlighted posts may appear higher in the news feed, stay visible for longer, and appear to more friends and subscribers. However, they’re not colored differently to make them stand out. And to be clear, this is not like Twitter’s Promoted Tweets which is designed for businesses. Facebook Highlight is for the end-user.

As part of Facebook’s experiment, some users are able to create a highlighted status update at no cost; others are asked to pay a dollar or two. Interestingly, it appears for the time being that paid Highlights can only be purchased with a credit card or PayPal, not with Facebook’s official ‘currency’, Credits.

According to a statement from Facebook, “this particular test is simply to gauge people’s interest in this method of sharing with their friends.” Judging from comments, it does appear that there is some interest, especially from those who use Facebook for marketing and self-promotion. Which isn’t surprising: on average, an individual user’s status updates reach just 12% of his or her friends, so Facebook doesn’t make it easy to distribute a message reliably (marketing or otherwise) to one’s social graph.

This could change that, but at what cost? While just an experiment, Facebook’s Highlight test is sure to raise questions about just how far the company is willing to go to make money now that it’s going to be a publicly-traded company. Pushing the limits might be good for the social network’s bottom line in the short term, but if the Facebook user experience fundamentally changes as a result of the company’s monetization efforts, all bets are off long-term.