Ashton Kutcher continues his expansion into all things internet, as it has just been announced that he has made a significant investment in travel startup Airbnb.

Airbnb is an online company that provides travelers the opportunity to ditch the hotel and stay in privately listed locations, from basic to extravagant. Users list their properties for rent and once travelers begin requesting their space, hosts have complete control on who they approve or deny. There is also a review system, for both host and lodger, built into the site. Airbnb has listings in over 8,000 cities and 166 countries across the world. They recently said that over 1.5 million nights have been booked using their service.

Airbnb announced the new partnership on their blog:

That’s right. It’s official. Ashton Kutcher – the man whose social media savvy made him a Twitter force to be reckoned with – has announced that he has made a significant investment in Airbnb and will be joining the team as a strategic advisor. The actor and angel investor’s love of science and technology is nothing new, but he has taken a fascination with tech to new heights with his avid approach to brand marketing and social media.

With Ashton on board, we’ll be working together to take our community engagement to the next level and expand our international presence to reach more people from different cultures all over the world. It’s an exciting time for us.

And if you’re looking to expand in the social market, you could pick worse guys to help you than Kutcher. His Twitter prowess is of legend, holding sway over nearly 7 million followers. Earlier this week he announced his own Twitter desktop app, powered by UberMedia called A+. The app carries some unique features but also allows Kutcher to promote his own projects and interests. It doesn’t take a professional prognosticator to see Airbnb integrated into his new Twitter app sometime in the near future.

Here’s what Kutcher said about Airbnb, as quoted in the NY Times:

“It’s moving social trust into commerce. Your home is a very private place, so building trust around turning that into a consumer offering is unlike any other site.”

Kutcher just signed a one-year contract to replace Charlie Sheen on Two and a Half Men, but it seems that he is devoting a lot of attention to the tech community these days. Kutcher has also invested in Flipboard and Path, among others.