Workman's article pretty well covers it, but for those new to the tale...in an effort to prove that naughty gun-dealers and gun-0wners were running guns across the Mexican border to sell to the drug cartels and other nasty folks that would then use them to do bad things, like killing US agents and supporting criminal empires - the ATF kids figured the best way to do this was to run guns across the border, and sure enough bad things happened and a couple of federal agents were killed with the guns that the ATF was running.
Poor form. As the great circling of the ATF wagon occurs, some nimrod got the bright idea of stonewalling Congress - failing to observe that things have rarely worked out well in the past for other federal agencies attempting that game. One might even suspect congress-critters get a bit cranky about such efforts.
Nevertheless, as usual, ATF is proceeding at full blunder ahead - failing to produce persons and documents that Senators and House members are demanding.
Who knows? We might get lucky and get to watch Congress abolish the ATF in favor of some worthwhile way to spend money....
See the article for latest developments