Indeed, the original trio boasts a combined net worth well over a billion dollars, rendering their lyrical prognostications accurate. They’re joined by Dr. Dre, flush with cash from his Beats headphone line, and Cash Money Records cofounder Bryan “Birdman” Williams.

“One of my motivations in life is to be a billionaire,” said Birdman in a telephone interview with FORBES. “We’re going to keep working hard until we get our brand to be as big as possible. That’s the goal in life, that’s what I live for.”

Diddy also boasts stakes in clothing lines Sean John and Enyce, marketing firm Blue Flame, record label Bad Boy and a handful of tech startups. But it’s his deal with Comcast to launch cable channel Revolt in 2013 that could push him into billionaire territory. He’ll own the channel outright, and based on projected viewership totals, its value could soar into the low-to-mid nine figures within the next few years.

Next up is Jay-Z at $460 million. Unlike his fellow Forbes Five members, Jay-Z still churns out music and goes on tour—most recently with pal Kanye West—adding to his considerable war chest. He sold his Rocawear clothing label for $204 million in 2007 and signed 10-year $150 million deal with Live Nation in 2008, and also holds stakes in the New Jersey Nets, his 40/40 Club chain, ad firm Translation, cosmetics company Carol’s Daughter and other businesses. (For more on his rise as a businessman, check out Zack’s Jay-Z biography, Empire State of Mind).

“Who’s going to be hip-hop’s first billionaire is still to be determined,” says Steve Stoute, the advertising guru who founded and co-owns Translation with Jay-Z. “But clearly Jay and Puffy are far and away positioned to surpass that.”

Dr. Dre ranks third with $270 million, doubling from a year ago thanks to a major sale. In August, handset maker HTC paid $300 million to buy a 51% stake in Beats Electronics, the company founded by Dr. Dre and Interscope chief Jimmy Iovine in 2008.

Sources say each owned a third of the company before the deal, placing Dre’s cut at $85 million after taxes. The agreement also values Dre’s remaining stake at $100 million, which could increase rapidly as the company continues to expand.

Birdman clocks in at No. 4 with a fortune of $125 million. He cofounded Cash Money Records with brother Ronald “Slim” Williams two decades ago, inking very favorable $30 million distribution deal with Universal in 1998. The label’s value is increasing with the success of rappers Drake, Nicki Minaj and Lil Wayne (who shares ownership of sub-label Young Money).

There’s even more on the horizon: Cash Money’s deal with Universal is up this summer, raising the prospect of a bidding war for the right to distribute the label’s releases.

“Right now we are with Universal and we’re just trying to do the best music possible,” Birdman told me. “I’m loyal to my team, and to success. Whoever gives the most benefit to my team, which is first, and to its success, that’s where we’ll end up at.”

Rounding out the Forbes Five is Curtis “50 Cent” Jackson at $110 million. The Queens-born rapper earned $100 million on the sale of his Vitaminwater stake in 2007—and tens of millions more from touring, record sales and clothing—but spent freely on cars and renovations to his mansion, formerly owned by Mike Tyson. Even so, a nice cushion remains from his back catalog, acting gigs and 50 Cent-themed videogames, shoes and books, as well as his new headphone line SMS. Next up: an energy shot called Street King, which promises to feed hungry children—and 50’s bank account.

Still, there’s no guarantee that hip-hop’s first billionaire will come from this group of five.

“As much as it’s easy to say it’ll be Diddy or Jay, you don’t necessarily know, given what a guy like Kanye or Will.i.am is capable of doing,” says Stoute. “In a world where people are creating applications that sell for a billion dollars, you never know who’s going to come out of left field.” -forbes.com