I don't know that she has become that much less annoying, but you can see they are starting to get to the Lois and Clark storyline and less away from Lana, at least in the last several episodes of the last season. She seems to have "grown up" a little. Every now and then you will see either Clark or Lois look at the other in a new light and see that they are getting closer to the relationship that is inevitable. Since the series was pretty much creating the previous lives and history of characters that we already know happen from all the movies and comics, I feel that they have been pretty creative with some of their histories and developed interesting relationships between the characters.
Besides, Chloe and Jimmy are on-again/off-again, so that even though she has feelings for Clark, she is with Jimmy and trying to make the best of that.
I think next season will be quite interesting in this aspect, since they have pretty much written Lana out - or seemed to at the end of last season, anyway.