This an exampe of a naive approach to sentiment analysis (if you can call it that way) in Spanish. I basically gathered a table with positive and negative words and evaluated the occurrence of them in a database of tweets from the twiter API.
This script is also useful for learning to query twiter's API, although you will need to get your keys directly at https://dev.twitter.com/
I've been looking for a more suitable corpus for Spanish sentiment analysis, but haven't found it yet.