My original plan had been to write up a quick summary of today's markup, but at this writing, the House Judiciary Committee has discussed less than half of over 50 pending proposed amendments to SOPA. However, there's a clear trend in the committee regarding amendments—nearly every one voted on so far has been defeated.
I'd been live-tweeting a blow-by-blow of the proceedings so far, but the main takeaways from the markup are probably best recounted thematically, rather than chronologically, since a lot of themes get repeated with each amendment 's introduction and debate.
There's various levels of debate being engaged in during this markup. First, there's the discussion of the bill text. Then there's the discussion of the bill's effects. Third is the discussion of proponents' and opponents' motives.