Как проанализировать yaml файл в рубин hashs и/или массивы?

Используйте модуль YAML:
http://ruby-doc.org/stdlib-1.9.3/libdoc/yaml/rdoc/YAML.html

node = YAML::parse( <<EOY )
one: 1
two: 2
EOY

puts node.type_id
# prints: 'map'

p node.value['one']
# prints key and value nodes: 
#   [ #<YAML::YamlNode:0x8220278 @type_id="str", @value="one", @kind="scalar">, 
#     #<YAML::YamlNode:0x821fcd8 @type_id="int", @value="1", @kind="scalar"> ]'

# Mappings can also be accessed for just the value by accessing as a Hash directly
p node['one']
# prints: #<YAML::YamlNode:0x821fcd8 @type_id="int", @value="1", @kind="scalar"> 

http://yaml4r.sourceforge.net/doc/page/parsing_yaml_documents.htm