Updating to RubyGems 1.3.0 on Mac OS X Leopard 10.5.4

When attempting to stall final release of Merb 1.0, I got an error message that I needed RubyGems version >=1.3.0:

ERROR:  Error installing merb:
 merb-core requires RubyGems version >= 1.3.

So I did the usual "gem update --system" but got an error:

$ sudo gem update --system
Password:
Updating RubyGems
Updating rubygems-update
Successfully installed rubygems-update-1.3.0
ERROR:  While executing gem ... (NameError)
    undefined local variable or method `remote_gemspecs' for #
$ gem --version
1.2.0

I found that you have to run a second set of instructions:

$ sudo gem install rubygems-update
Successfully installed rubygems-update-1.3.0
1 gem installed
$ sudo update_rubygems 
Installing RubyGems 1.3.0

More info here:
http://rails.wincent.com/wiki/Updating_to_RubyGems_1.3.0_on_Mac_OS_X_Leopard_10.5.4