Topguest, an 18-month-old start-up focused on loyalty programs and travel, already is checking out. The company, which lets users earn loyalty points from check-ins, photos and updates, has been acquired by travel software company ezRez. Terms of the deal were not disclosed.

Topguest members check-in using Facebook, Foursquare, Instagram and Twitter and earn loyalty bonuses from programs, including UnitedMileagePlus, Continental OnePass, IHG Priority Club and Hilton HHonors. EzRez, itself founded in 2003, says the acquisition complements its own suite of loyalty programs.

Daniel Farrar, ezRez's CEO, said Topguest’s social media solutions "provides the missing piece in our product suite relative to where travel is going."

Topguest will continue to operate under its current branding, though the team will relocate to ezRez's San Francisco headquarters. The companies eventually will join forces on a product that will let Topguest users, for example, redeem their points for more than just travel. They'll also be able to cash them in for products from online retailers that accept Paypal.

"We created Topguest to help travel companies tap into the social behavior of consumers, while enabling these consumers to earn more rewards and receive offers relevant to them," Geoff Lewis, Topguest's CEO and co-founder, said in a statement. "The team at ezRez shares our philosophy that loyalty programs can and should go beyond their traditional models and we’re excited about joining forces to make a long-term impact on the industry while also bringing tangible benefits to consumers."

Topguest closed a $2 million round of funding in 2010. Paypal co-founder Peter Thiel also was an adviser and his Founders Fund was an investor. (Lewis used to work for Thiel as the vice president of marketing at Clarium Capital, a hedge fund run by Thiel.)

The company actually started out in New York in July 2009 with a different product: Udorse, where users would take pictures and tag them (basically endorsements of products or locations) and earn rewards. But Lewis said the idea wasn't scalable, so he and his four co-founders scrapped the idea and turned to Topguest. EzRez raised $17 million in two rounds of funding, the second of which was $15 million in 2007.