If you’re trying to reach someone with a data signal, the D Block is a good thing to have. It can penetrate concrete walls, get through buildings, find its way down in a parking garage. The federal government is required by current rules to auction this bit of bandwidth off to wireless carriers. But that’s not a sure thing.

A House subcommittee is holding a hearing on the future of the D Block today. Many House Republicans want the auction to go forward since it would raise about $3 billion. That $3 billion has already been factored in to many budget projections. The idea is that even though a wireless carrier might control the D Block, they would share it in a time of national emergency.

But there’s a broad coalition of opponents who want to change the rules and block the auction from taking place. This includes congressional Democrats, some Republicans, the Obama administration and at least two former 9/11 Commission members.

Adding to the mix are the wireless carriers. AT&T and Verizon already have sections of the spectrum in use that are relatively similar to the D Block; they’re opposing the auction. But Sprint and T-Mobile see this as a way to compete with the bigger companies. Complicating matters: the fact that AT&T and T-Mobile are looking to merge.

We talk to Glenn Fleishman from The Economist online about what this spectrum is and what’s at issue here. We also talk to Tony Romm from Politico about the battle lines being drawn and what this could all mean in the long run.

Also in this program, a Maine school district is planning to give iPad 2s to all incoming kindergarten students. We talk to a 5-year-old kindergartner-to-be about what she would do with an iPad 2.