Rからerb記述が含まれるyamlを読み込む ref: http://qiita.com/foloinfo/items/9ce4662953f9ace094e1

file0.r

> system('ruby -e "puts 1+1"', intern=TRUE)
[1] "2"
> system("ruby script.rb", intern=T)

file1.txt

require 'erb'
p ERB.new(File.read('database.yml')).result

file2.r

yaml.load(yaml.load(system("ruby load_erb.rb", intern=T)))

$test
$test$adapter
[1] "sqlite3"

$test$database
[1] "db/test.sqlite3"

$test$pool
[1] 5

$test$timeout
[1] 5000

file3.r

eq <- "ruby -e 'require \"erb\"; p ERB.new(File.read(\"database.yml\")).result'"
yaml.load(yaml.load(system(eq, intern=T)))

file4.r

yaml.load_erb <- function(path){
 eq <- paste("ruby -e 'require \"erb\"; p ERB.new(File.read(\"", path,"\")).result'", collapse='', sep='')
 yaml.load(yaml.load(system(eq, intern=T)))
}