authorize_token! method

returns always RubyPicasa::PicasaTokenError, 'The request to upgrade to a session token failed.'
I think you should replace /accounts/accounts/ by /accounts/ in http request. It's works for me

def authorize_token!
http = Net::HTTP.new("www.google.com", 443)
http.use_ssl = true
response = http.get('/accounts/accounts/AuthSubSessionToken', auth_header)
token = response.body.scan(/Token=(.*)/).flatten.compact.first
if token
@token = token
else
raise RubyPicasa::PicasaTokenError, 'The request to upgrade to a session token failed.'
end
@token
end