While almost all the women had either a French manicure or a simple clear polish, Ginnifer Goodwin's character, Gigi, had metallic purple nails. If I'm not mistaken, there were two different shades: one lighter and more on the lilac side, the other dark and very purple, maybe with a bit magenta in it.
Purple polish is not the easiest to pull off, especially on skin with yellow or olive undertones. Personally, I'm more into mauve, but you just can't deny how pretty it is- in theory and on Ginnifer's hands. Here are some options for this look:
Essie It's genius (left) and China Doll (right):
Zoya has a great selection of purples with different levels of shimmer. Several of their colors could have easily been the one(s) from He's Just Not That Into You, but I have a soft spot for Juno, though I probably shouldn't wear it:
Different than the purples in the movie (and not entirely wearable for the olive skinned), but interesting and worth mentioning is Purple Rain from the Lippman Collection, originally created for Zac Posen's Spring 2009 collection:
Do you have a favorite very purple polish?