$ for ver in `rvm list strings` ; do rvm use $ver ; ruby bm.rb ; echo ; echo ; done
Using /Users/josh/.rvm/gems/jruby-1.5.2
      user     system      total        real
for loop    1.435000   0.000000   1.435000 (  1.435000)
while loop  1.034000   0.000000   1.034000 (  1.034000)
times loop  1.126000   0.000000   1.126000 (  1.126000)


Using /Users/josh/.rvm/gems/jruby-1.5.3
      user     system      total        real
for loop    1.215000   0.000000   1.215000 (  1.214000)
while loop  0.832000   0.000000   0.832000 (  0.832000)
times loop  1.075000   0.000000   1.075000 (  1.075000)


Using /Users/josh/.rvm/gems/macruby-0.7
      user     system      total        real
for loop    0.300000   0.010000   0.310000 (  0.326895)
while loop  0.170000   0.000000   0.170000 (  0.194720)
times loop  0.290000   0.000000   0.290000 (  0.317413)


Using /Users/josh/.rvm/gems/rbx-1.1.0-20100923
      user     system      total        real
for loop    0.659698   0.002758   0.662456 (  0.604091)
while loop  0.273308   0.000836   0.274144 (  0.282022)
times loop  0.465803   0.001229   0.467032 (  0.473257)


Using /Users/josh/.rvm/gems/ruby-1.8.6-p399
      user     system      total        real
for loop    1.310000   0.000000   1.310000 (  1.370652)
while loop  2.530000   0.010000   2.540000 (  2.632887)
times loop  1.400000   0.000000   1.400000 (  1.445486)


Using /Users/josh/.rvm/gems/ruby-1.8.7-p249
      user     system      total        real
for loop    1.330000   0.000000   1.330000 (  1.401758)
while loop  2.580000   0.000000   2.580000 (  2.656171)
times loop  1.400000   0.010000   1.410000 (  1.468186)


Using /Users/josh/.rvm/gems/ruby-1.8.7-p302
      user     system      total        real
for loop    1.350000   0.000000   1.350000 (  1.409171)
while loop  2.780000   0.010000   2.790000 (  2.894848)
times loop  1.440000   0.000000   1.440000 (  1.497513)


Using /Users/josh/.rvm/gems/ruby-1.9.1-p378
      user     system      total        real
for loop    0.600000   0.010000   0.610000 (  0.620772)
while loop  0.300000   0.000000   0.300000 (  0.314391)
times loop  0.560000   0.000000   0.560000 (  0.575759)


Using /Users/josh/.rvm/gems/ruby-1.9.2-p0
      user     system      total        real
for loop    0.630000   0.000000   0.630000 (  0.657867)
while loop  0.310000   0.010000   0.320000 (  0.327625)
times loop  0.580000   0.000000   0.580000 (  0.671073)