If you "like" Corralco's Facebook page, and follow it, they provide a lot of information on snow conditions, pretty much daily. You need to be able to read Spanish, however. Valle Nevado's page seems to be more fluff (no pun inteneded), with lots of photos of people. However, they just came out with an iPhone app, assume they have an Android version too, that provides a lot of information. I just got it, so can't speak to whether or not its updated regularly.
I'll be going to Corralco in a couple of weeks and can provide a report. Haven't had the motivation to get up to one of the resorts here in Santiago yet, but when I'll do, I'll post a report.