Urbanspoon -- the wildly popular online restaurant directory -- is hosting a big bash tonight in Seattle's Capitol Hill neighborhood. No specific reason was given for the party in the invite, but the company certainly has a lot to celebrate: a recent acquisition by IAC and an iPhone app that's recorded six million downloads. 

But could there actually be some news coming at the event? 

My former P-I colleague Rebekah Denn -- who now writes the Eat All About It blog --  reports that Urbanspoon has quietly begun testing an online restaurant reservation system in Seattle. That's significant because online restaurant reservations for the longest time have been dominated by one player: San Francisco-based OpenTable.

Still, the competition looks to be heating up. Visitors to the Urbanspoon Web site or iPhone app can now book reservations at a few select Seattle restaurants, including Rover's, Matt's in the Market and Dahlia Lounge.

Of course, that's not even crumbs compared to OpenTable which now boasts 10,000 restaurant customers and has seated some 100 million diners in the past 11 years. Last year, OpenTable recorded revenue of $55.8 million -- a strong enough showing that the company navigated one of he worst IPO markets in history to price shares in a very healthy Nasdaq debut in May.

Could Urbanspoon -- now part of Barry Diller's Internet war chest at IAC -- take a seat at the online reservation table?

It is too early to say, and we've yet to hear back from the founders of Urbanspoon on the matter. (I chatted with the team after our radio appearance on KUOW last month, and they hinted that a new service was in the works. Maybe this is it).

Denn -- who interviews Eric Tanaka of Tom Douglas Restaurants -- offers some interesting analysis on how this might play out.

Tom Douglas Restaurants, which operates Dahlia Lounge and already utilizes OpenTable, expects the Urbanspoon service to hit a different user base since at this time it is only being tested for same-day reservations. (OpenTable, on the other hand, allows reservations up to a year in advance).

Urbanspoon's service shows times that tables are available that night -- leading Denn to conclude that the service would be extremely helpful for a person who was leaving a movie theater and wanted to shake his or her phone in order to see if a nearby restaurant had any space available.  

Denn also observes that there could be some integration issues with OpenTable, which probably won't take too kindly to a young, upstart waltzing in to its core business. Denn writes:

In the beta version, at least, the Dahlia is paying the same $1/head to Urbanspoon as it pays Open Table. It isn’t, though, on the hook for startup costs or monthly fees or a dedicated terminal, assuming the restaurant already has a working iPod or iPhone. But that’s also part of the downside. Since Open Table didn’t want to sync its system with Urbanspoon, Tanaka said, (no surprise there) the restaurant needs to hand-enter its Urbanspoon reservations into its Open Table system. Ouch.

Obviously, that creates logistical challenges in a busy restaurant environment. Nonetheless, it will be fascinating to see where this goes.

Denn's watching closely too: "...I’ll be waiting to see if either group winds up eating the other’s lunch," she writes.

John Cook is co-founder of TechFlash. Follow on Twitter @johnhcook.