Cellular Surprise for Political Polling?

Even as we enjoy new capabilities for gauging political opinion around the world, a nagging technology development haunts opinion polling here in the USA. The uncertainty suggests room for “surprises” come November.
Americans are increasingly ditching conventional telephones in favor of “cellular” and “internet phone” options. (“skype,” vonage, etc.) 15% or more of the American voting population now uses cellular phones only. The trend away from land lines may be accelerating, now that major telecommunications carriers (like Verizon) permit customers to sign up for DSL (or FiOS) without having a conventional phone line.
Pollster are aware of the potential problems, but most polling has shied away from sampling cellular-only citizens. Why? Practically, it’s considerably more expensive. First, there’s the difficulty of accessing cell phone listings. Second, regulations forbid automated calling of cell numbers. Then too, what does a statistician do with those who keep their old cell phone numbers when they move to new locations? And most disconcerting, how do you convince someone to stay on the line to answer a survey, when that person may be paying 25-50 cents per minute for the call? Answer: — you have to compensate them. (assuming subjects don’t hang-up first!)
How do pollsters rationalize excluding 15% of the population? I gather that received wisdom deems the sampling problem to be theoretical — that is, of no consequence, a “wash.”
Yet we do have new data suggesting otherwise. Consider a recent Pew Research Center for the People & the Press analysis of three Pew presidential surveys that included cellular sampling:

In each of the surveys, there were only small, and not statistically significant, differences between presidential horserace estimates based on the combined interviews and estimates based on the landline surveys only. Yet a virtually identical pattern is seen across all three surveys: In each case, including cell phone interviews resulted in slightly more support for Obama and slightly less for McCain, a consistent difference of two-to-three points in the margin.

I’m not quite squaring the phrase “not statistically significant” with “virtually identical pattern.” Furthermore, the study observes:

in each of the three polls, the cell-only respondents were significantly more supportive of Obama (by 10-to-15 percentage points) than respondents in the landline sample. For example, in the September survey Obama led McCain by a 55%-to-36% margin among cell only voters, but the candidates were tied at 45% in the landline sample.

Pew isolates “age” as the explanation for this considerable difference: “In large part, this reflects the fact that a substantial minority of the cell-only sample is younger than 30 – a demographic group that has consistently backed Obama this year.”
If I were a pollster, I’d be starting to sweat. Some firms apparently are debating “adjustments” to account for the youth/cell factor – the one that supposedly is not yet “statistically significant.” (If any jwn readers can explain that solution in “plain english,” please chime in.)
By way of disclosure, I’m about to cancel my own land-line. I’m the last hold-out in my family. While I too am tired of the daily push-poll calls from this or that candidate (another subject!), my motivation is personal – I’m getting even with Sprint/Embarq for never delivering dsl. If the pollsters want to find me, they’ll have to call my unlisted cell.