Online restaurant guide Urbanspoon is now part of the IAC (NSDQ: IACI) portfolio, adding more local flavor to the mix with Citysearch. The acquisition was announced this morning with the company’s Q1 earnings but actually took place Feb. 13; no financial details were disclosed but IAC has been vocal about staying with tuck-in acquisitions and I believe this one to be in the low double-digit millions. (That would be far below IAC’s $100 million self-imposed limit.) Release.

Seattle-based Urbanspoon was cofounded in 2006 by Ethan Lowry, Adam Doppelt and Patrick O’Donnell; yes, it was a site before it was a popular iPhone app boosted by its appearance in Apple (NSDQ: AAPL) ads. It will remain an independent brand and a wholly-owned subsidiary of IAC, reporting to Citysearch CEO Jay Herratti; he also oversees InsiderPages and Evite. It currently covers the U.S., Canada, the UK and Australia.

IAC ramped up its local strategy earlier this year, taking Citysearch’s redesign out of beta and announcing a partnership with MySpace for MySpace Local . Urbanspoon’s content will be integrated across IAC’s local sites, including Citysearch and InsiderPages. The food site has been part of the Citysearch Partner Network since 2008, so was already using Citysearch local content before the acquisition.

IAC’s description of the deal: “Urbanspoon rounds out a portfolio of premium local brands which include Citysearch, ServiceMagic, InsiderPages, and strategic investments in OpenTable and MerchantCircle. With a wealth of trusted restaurant content, an avid user community, and a leading iPhone application, the acquisition of Urbanspoon will further solidify IAC’s leadership role in the local space.”

In its Q1 earnings release today, IAC said the Urbanspoon and Citysearch apps have been downloaded more than 4 million times; the bulk of that is likely Urbanspoon. (The company also said its Dictionary.com app has been downloaded more than 1 million times since it debuted on April 8.) Urbanspoon has achieved near-iconic iPhone status for its app, which includes the ability to shake the phone for GPS-based dining suggestions.

Update: TechCrunch has more from an interview with cofounder Lowry.