Google (NSDQ: GOOG) execs sidestepped questions about the 700 MHz spectrum auction underway and even WiMax during today’s Q407 earnings call. Chairman and CEO Eric Schmidt: “We’ve concluded we cannot answer any questions in that category because of legislative rules with respect to how the auction is working.”

Citigroup’s Mark Mahaney came at mobile form a different direction and got plenty of words. The analyst asked about mobile internet usage, particularly iPhones. “Is there any way you could quantify it and is there a way you think about how mobile search as a percentage of overall search could be in two to three years?”

Schmidt: “It’s very difficult to estimate the percentage in a few years. We have already said in a number of public statements that it is growing significantly faster on a percentage basis than other categories, and as you mentioned, iPhone is the first of a whole generation of products that will be much more search intensive, and so there’s much more likely to be many more search opportunities and with those search opportunities comes ad monetization.  He mentioned Google’s various deals, including KTTI and DoCoMo (NYSE: DCM), then continued: “It’s difficult to estimate what percentage it could ultimately be long term—and when I say long term, I mean perhaps 10 or 20 years. It’s reasonable to assume that a majority of searches would be on mobile or personal devices, simply because over a long enough period of time, they will take on the tremendous power that’s represented in the PC and Mac platform. And the wireless networks are getting to the point where they can offer performance similar to the wireline.”

Jonathan Rosenerg added that Google is tracking the data “very carefully” and that the iPhone is particularly interesting “because the experience on web browsing is so good and because of the optimization efforts which we did. We saw a very significant spike in December ... and it was well over double, I think, within about a month in terms of increased usage.”

Listen to the call or check out the transcript at SeekingAlpha.com for more.