Will firms need to weed more people out than usual? Of course they will, in those firms that significantly over hired. I think mediocre (or poor) 2L grades might be something to "cite" to if they wanted to no offer but honestly, I really see much more attention paid to situations where someone would criticize work product (poor proofing, missed a main case, writing jumbled and not coherent, missed the big issue), production (not on time, not what was asked, etc) or firm fit (perceived insult to staff member, too nervous/anxious, etc.). So, the long answer to your short question is that I don't see 2L grades being such a significant factor.
One of our female readers asked about how many suits one should have and if four is enough where there's a Friday business casual. I would say to start out, 4 should be ok, but if you can, pick up something once you have a little summer moolah to add - what if one of these suits gets a cup of coffee spilled on it -- it would be good to have a substitute. For men, I think 4 is enough. I've asked around on this one and one of my friends had a good add -- and that is women can also usually do some mixing and matching with accessories and tops and such so that it doesn't appear you are wearing the same 4 suits week after week.
On the subject of socializing, I thought F-3's ideas, as always, were good ones. F-3 is HP's teacher pet here. Actually, I do not know F-3, but F-3 does usually have insightful things to say. I will speak to this more perhaps next time. You do not have to be the "life of the party." The key is to be on time, pleasant, sociable, and not offend. I agree it is helpful to be able to comment on different (hopefully non-controversial) topics. I have a close friend from law school. She was once at a post-screening day recruiting cocktail thing with a bunch of lawyers from a big NY firm. A few others from her law school were at the table with these lawyers. Pleasant chit chat ensued. Obviously, all the law students wanted to make an impression. One by one, however, they had to catch planes, trains. My friend had some time. Instead of leaving with the others, she stayed. So it was her and about 4 male attorneys, including some senior partners. They talked about where friend is from. Friend is from a big sports city. They started talking about sports teams. Friend could talk about sports teams, told stories about going to the ball games in her youth, what players she liked, how a former player coached at her college etc. Friend was invited back and did in fact get a 2L offer from this firm. Of course, friend's grades helped a lot, but I have no doubt that it was friend's ability to carry on chit chat with strangers that helped friend make that impression.
OK, HP's dog needs to go a walkin so HP's gotta go.