Some nine months after Google made its bid for an acquisition of airfare gurus ITA, the Justice Department has approved the transaction. Soon, according to the Google Blog, you’ll be able to search for “flights to somewhere sunny for under $500 in May” and Google’s software will mesh with ITA’s in order to allow you to purchase just that.

Of course, there are some stipulations. ITA is the software that is primarily responsible for the booking of all flights in the US, and as such many other outlets (read: Expedia, Priceline, et al) were all very interested in Google’s new role.

According to the Justice Department, Google has some pretty big responsibilities:

Google will be required to continue to license ITA’s QPX software to airfare websites on commercially reasonable terms…Google will also be required to continue to fund research and development of that product at least at similar levels to what ITA has invested in recent years. Google will also be required to further develop and offer ITA’s next generation InstaSearch product to travel websites, which will provide near instantaneous results to certain types of flexible airfare search queries.

Of course you can almost bet on us seeing arguments from both sides about the definition of “commercially reasonable terms”, as well as the rest of the points in the JD’s plan.

For now, at least, it should be interesting to see exactly what Google does with the software and ideas that come out of ITA.