I have no idea what the GOP leadership knew about Mark Foley and when they knew it. If anyone sat on information that the guy was sexually stalking kids, they were acting like a political moron and moral cretin. If that includes Denny Haestert, so be it.
But I think a few rules should govern the feeding frenzy that we're in. First, we should be careful about ascertaining just what was supposedly known. It would be one thing to know that Foley sent and "overly friendly" e-mail (without sexual language or innuendo). That might concern someone (50-something year old guys are not usually big buddies with 16 year old kids), but not constitute anything that could be really be acted upon. I have no hope that this distinction will be respected, since we conduct our political dialogue in bad faith these days.
Second, the question of "knowledge" is not just for Republicans. If Dems knew about Foley's more troubling communications and said nothing. Or waited until the most politically propitious moment, they are just as culpable. The GOP may be running the House, but if a Democrat knew about Foley and sat on it, he or she may not the as much of a political moron, but is just as much a moral cretin.