One of the moments that I found remarkable in the latest chapter was definitely when Nami declared that she wants to save those children. Especially because of Sanji's reaction to it.
The situation is the following: The Straw Hat Crew are pirates, which per definition is something bad. But we all know that, apart from fighting some Marines and beating the living crap out of a bunch of jerks who deserved even more beating than they actually got, they never did anything that can be considered bad. In fact all they did so far was helping the people they considered friends and freeing several nations of their corrupt leaders or prevent the uprise of such along the way.
But that is the point: They usually did it in order to help a friend or crew member (with exception of Skypiea maybe; I don't even remember much about that arc). As Sanji put it: They don't run a charity business. All they did so far was more or less for personal gain.
So what happened here in 658? Basically, something similar as in chapter 47 and onward. A character's believes and moral standards are established by putting them into a contrast to the current situation.
In chapter 47 Sanji and Zeff gave Krieg and his men food despite Krieg's behavior towards them. In chapter 658 Nami, the most selfish Straw Hat member after Luffy, decides to save a bunch of kids she just met despite being in a situation when she should be thinking about herself first. And not just along the way as the SH usually save bystanders but intentionally. (Note the shot! We see Nami's tattoo quite clearly, which is probably supposed to remind us to her past and make us understand her motives.)
As much as I hate Nami I think it's awesome that Oda decided to do some character development outside the characters joining arc again. So far it was only Zoro and Usopp (Luffy doesn't count because he's the main character). I really hope for more in the future arcs, especially for Franky and Robin.