I think that first year grades are really important at all schools b/c everyone wants to have that impressive associate position at the most prestigous firm in town on their resume. However, I think that for the most part, the summer associate position for a 1L is just that. See most firms realize that 1Ls don't really know that much just yet. So it doesn't matter too much how great the relationship was b/c they will still choose someone that has a great cumulative GPA and has tailored his classes to the firm needs over someone who seemed like a good kid. Sure it doesn't hurt that you worked there, but I don't think that it's such the "in" that everyone makes it out to be.
Now, in the second year...that's a different story.
Well, as far as grade trends, most ppl at my school get more B+/A-/As as a 2L and 3L since the classes are small so the mandatory curve is no longer in effect.