Sam Gustin writes: Pop star Britney Spears is staging a comeback. Her new single "Womanizer" is topping the charts; the full record will be released in December. So, like any self-respecting pop superstar, Spears has joined Twitter.

That's right, Britney Spears in on Twitter. (As well as Facebook, MySpace and YouTube.)

Spears' adoption of Twitter is aimed at the hearts and minds -- not to mention computer screens, mobile phones, and ultimately, wallets -- of a generation of youngsters born too late to experience the first round of Spears-mania from 1998-2000 but old enough to know be right at home with the latest Web 2.0 services.

What's more, Spears' decision to use Twitter could point the way toward profitably for the popular, business-model-challenged micro-blogging service.

Spears' newly revamped website offers fans the opportunity to "friend" the star on Facebook, MySpace, and Twitter.

"I wanted to create a place where I could connect with ya'll and share what's really going on in my life. I'll be sharing videos, stories, music, photos, and lots of other cool stuff," Spears said in a statement.  "OMG!! 7 hours until Womanizer premieres!!!!!!!," read one update anticipating the debut of Spears' new single "Womanizer," which has shot to the top of the music charts, thanks to a strong digital download showing on iTunes.

It's pretty clear that Spears herself isn't responsible for most -- if not all -- of these blog posts and Twitter updates. Many of them are written in the third person or signed by "Jennifer, Team Britney."

But when it comes to Twitter, the medium is the message, and Spears' embrace of the service opens a new channel of communication to her fans.

Spears' Web makeover comes amid the latest bout of hand-wringing over how Twitter plans to make money. On Friday, Twitter investor Fred Wilson, of Union Square Ventures, boiled over after being asked by Wired.com about the company's business model.

"It's like the stupidest question in the world: How's Twitter going to make money?" said Wilson. "It's like 'How was Google going to make money?'" He added:  "Eventually Google was going to make money and they figured out how to do it and they figured out a great business, and I think the same thing is true with Twitter."

Wilson quickly thought better of the comparison and posted an explanation on his blog, writing, "The minute I said it, I wanted it back."

"It is not the stupidest question in the world. It's a terribly important question," Wilson wrote. "But I don't think it's the most important question facing Twitter right now. Twitter has yet to cross the chasm to mainstream usage. It's not immediately obvious to anyone why they should use Twitter."

Spears' adoption of Twitter highlights an obvious revenue stream for the company, which has struggled to present a coherent business plan: Charge businesses for the right to send commercial messages on the service. But here Twitter has run into a problem familiar to other online social networks searching for a path toward profit: people use these services to mingle with others, not because they're looking to buy products.

After months of enduring the same question -- "What is Twitter's business plan?" -- Twitter shook up its top management late last week, replacing Jack Dorsey with Evan Willams as CEO.

"We all think Ev is a better fit to lead the company from a product perspective, an operations perspective, and a business standpoint," Wilson said.

Translation: It's time to make some money off this thing.