What is the _snowman param in Ruby on Rails 3 forms for?

This parameter was added to forms in order to force Internet Explorer (5, 6, 7 and 8) to encode its parameters as unicode. Specifically, this bug can be triggered if the user switches the browser's encoding to Latin-1. To understand why a user would decide to do something seemingly so crazy, check out this google search. Once the user has put the web-site into Latin-1 mode, if they use characters

[yyamano]

3.2ではutf8という名前のparameterに変わってるっぽい。