Celebrity invasion! Jay-Z, JHud and Playmates, oh my!

It will be a mixed bag of VIPs in Las Vegas this weekend, as Jay-Z, Hugh Hefner, and Mariah Carey all planning trips to town.

Meanwhile, a handful of motocross riders join perennial Vegas partiers Mario Lopez and Kourtney and Khloe Kardashian at separate scheduled appearances.

DC Motocross teammatesJeremy McGrath, Ricky Carmichael, Robbie Maddison, Nate Adams, Adam Jones, Josh Hill, Davi Millsaps, and Dustin Miller will sign autographs and take pictures with fans on Friday afternoon, from 3 p.m. until 5 p.m., at their sponsor’s new store at the Miracle Mile Shops.

Over at the Palms and fresh off a stint in Costa Rica, big time nightlife promoter-slash-tattoo-artist John Huntington will officially mark his return to Las Vegas this weekend as he rebrands/opens his own/new tattoo parlor on Friday.

The shop, Huntington Ink, will replace the “Inked” star’s previous commercial collaborative effort with Carey Hart, Hart and Huntington, which previously occupied the same space.

Huntington will host at Ghostbar next week, along with a group of so-called “ink girls.”

While Huntington celebrates inside the casino, things will heat up around the pool at Palms Place and Bungalows as the 2009 season of Ditch Fridays gets underway.

A bikini-clad cast of 2008 Playmates – including Michelle McLaughlin (February 2008); AJ Alexander (May 2008); Juliette Frette (June 2008); Laura Croft (July 2008); Kayla Collins (August 2008); Kelly Carrington (October 2008); and identical twin sisters Jennifer and Natalie Campbell (December 2008) – will host the sexy afternoon splash fest.

Also at the Palms on Friday, Euro sensation Hedkandiwill take over the turntables at Moon, along with DJs Phil Faversham and Airloom.

Meanwhile, Robin Thicke and Jennifer Hudson will play the Pearl.

In a curious and odd change-of-venue, the official Thicke-Hudson after party will be held at Privé at Planet Hollywood.

Despite the Grammy and Academy Award-winners at the Palms, however, the biggest star of the night will shine over at Lavo, as rapper Jay-Z puts in his first of two nights as a Las Vegas nightclub host.

No appearances by his better half, Beyoncé Knowles, have been announced – but here’s hoping.

With or without Beyoncé, the former Def Jam CEO and 40/40 Club co-founder will be at Tao on Saturday to host yet another night of fun in da club.

Jay-Z will likely pop by his own nightspot at the Palazzo at some point this weekend, as well – perhaps even tonight, if he’s in town. If not, the odds will definitely be in the house’s favor that he will stop by 40/40 at some point later this weekend, after his commitments with Lavo on Friday, or Tao on Saturday – or both.

Rarely one to keep fans guessing, Playboy mogul Hugh Hefner announced weeks ago that he will be at Simon at Palms Place on Saturday night to announce the 50th Playmate of the Year.

Former Celebrity Apprentice contestant and former 2001 Playmate of the Year, Brande Roderick, will host the event, while several other Playmates past will also be in attendance.

Hef and his bevy of beauties will host the official after party later that night at – where else?! – Playboy Club.

Over at Planet Hollywood, Mario Lopez will host a night at Privé.

Further south on The Strip, at MGM Grand, the cast of “True Blood” will come together for a second season kick-off party at Tabu.

Anna Paquin, Stephen Moyer, Sam Trammel and Alexander Skarsgard are among those expected to walk the red carpet at midnight.

Kourtney and Khloe Kardashian will appear alongside NBA great Robert Horry on Saturday at Sapphire Pool at the Rio as the adults-only pool holds its season opener soirée.

The evening party kicks off at 7 p.m. and will feature a performance by Alisa Apps. The three-hour celebration will support the Prostate Cancer Foundation and admission is by donation, with a $10 minimum.

As the weekend’s supercross series comes to a close, Carey Hart will throw a party at his hardcore club at the Hard Rock, Wasted Space. A collection of hand-painted 59FIFTY hats will be auctioned off during the party.

The hats’ unique designs were created and executed by Hart and Huntington tattoo artists, and proceeds of the sale will support the Road 2 Recovery Foundation, which helps professional motocross racers who have suffered career-ending injuries.

VIPs expected to attend include motocross greats Chad Reed, Davey Millsap and Josh Grant. Hart will be there, too, but let’s face it: That goes without saying.

Space Miami resident DJ, DJ Oscar G will heat things up on Sunday as he spins an afternoon set at Tao Beach.

Meanwhile, England’s own Ricky “The Hitman” Hatton will host an afternoon of fun in the sun at Wet Republic, regardless of the outcome following his fight against Manny Pacquiao the night before.

Hatton is expected to arrive at 3 p.m. to will host the Wet Republic’s weekly “Daylife Sundays” pool party.