Technically he did not report it as fact, he was "just asking questions," which is typical of Fox News and Glenn Beck in particular. This way, they aren't technically lying to you, they just get to report lies. The other common method is "People are saying Barack Obama ate a puppy yesterday." Yes, technically some people are saying that. Like the crazy person you just had on your show, Hannity. But if your organization was a legitimate news organization you would have bothered to check and see if Obama had actually eaten a puppy, discovered he hadn't, and then not reported it as news.
Using the same ACORN situation, Fox News' Morning Dip****s show had James O'Keefe on the air soon after the "scandal." O'Keefe was dressed in the pimp outfit you saw in the video on Fox News. One of the idiots on the morning show mentioned he'd worn that in the ACORN office. O'Keefe didn't deny it, but he didn't affirm it either. Technically O'Keefe didn't lie. Now, anyone could have known for a fact that O'Keefe hadn't actually worn that outfit in the ACORN office. This information was out there. The impression from the video tape was false. His excuse was "Oh that was just B-roll stuff!" But Fox n Friends didn't check.
Because nobody on that network is actually a journalist. They are a network devoted to pushing an agenda and will do anything and everything to further that agenda. They'll even actually tell lies, deliberately. They fought a wrongful termination lawsuit regarding that, and their defense was that lying on the news isn't illegal, so firing reporters for refusing to lie isn't wrongful termination covered by whistleblower laws.
So, did Glenn Beck lie? Not technically. But the effect and intention is still to deceive you.