error message I received after installing Xcode command line tools:

gistfile1.txt

\curl -#L https://get.rvm.io | bash -s stable --ruby
######################################################################## 100.0%
Please read and follow further instructions.
Press ENTER to continue.
Downloading RVM from wayneeseguin branch stable
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 1616k  100 1616k    0     0   148k      0  0:00:10  0:00:10 --:--:--  238k

Upgrading the RVM installation in /Users/rickthomas/.rvm/
    RVM PATH line found in /Users/rickthomas/.bashrc /Users/rickthomas/.zshrc.
    RVM sourcing line found in /Users/rickthomas/.bash_profile /Users/rickthomas/.zprofile.

Upgrade Notes:

  * No new notes to display.

# RVM:  Shell scripts enabling management of multiple ruby environments.
# RTFM: https://rvm.io/
# HELP: http://webchat.freenode.net/?channels=rvm (#rvm on irc.freenode.net)
# Cheatsheet: http://cheat.errtheblog.com/s/rvm/
# Screencast: http://screencasts.org/episodes/how-to-use-rvm

# In case of any issues read output of 'rvm requirements' and/or 'rvm notes'

Upgrade of RVM in /Users/rickthomas/.rvm/ is complete.

# Rick Thomas,
#
#   Thank you for using RVM!
#   I sincerely hope that RVM helps to make your life easier and
#   more enjoyable!!!
#
# ~Wayne


rvm 1.18.18 (stable) by Wayne E. Seguin <wayneeseguin@gmail.com>, Michal Papis <mpapis@gmail.com> [https://rvm.io/]

Searching for binary rubies, this might take some time.
No binary rubies available for: osx/10.7/x86_64/ruby-2.0.0-p0.
Continuing with compilation. Please read 'rvm mount' to get more information on binary rubies.
Fetching yaml-0.1.4.tar.gz to /Users/rickthomas/.rvm/archives
Extracting yaml to /Users/rickthomas/.rvm/src/yaml-0.1.4
Configuring yaml in /Users/rickthomas/.rvm/src/yaml-0.1.4.
Compiling yaml in /Users/rickthomas/.rvm/src/yaml-0.1.4.
Installing yaml to /Users/rickthomas/.rvm/usr
Fetching openssl-1.0.1c.tar.gz to /Users/rickthomas/.rvm/archives
Extracting openssl to /Users/rickthomas/.rvm/src/openssl-1.0.1c
Configuring openssl in /Users/rickthomas/.rvm/src/openssl-1.0.1c.
Compiling openssl in /Users/rickthomas/.rvm/src/openssl-1.0.1c.
Installing openssl to /Users/rickthomas/.rvm/usr
Updating openssl certificates
Installing Ruby from source to: /Users/rickthomas/.rvm/rubies/ruby-2.0.0-p0, this may take a while depending on your cpu(s)...
ruby-2.0.0-p0 - #downloading ruby-2.0.0-p0, this may take a while depending on your connection...
ruby-2.0.0-p0 - #extracted to /Users/rickthomas/.rvm/src/ruby-2.0.0-p0 (already extracted)
ruby-2.0.0-p0 - #configuring
ruby-2.0.0-p0 - #compiling
ruby-2.0.0-p0 - #installing 
Retrieving rubygems-2.0.3
There is no checksum for 'http://production.cf.rubygems.org/rubygems/rubygems-2.0.3.tgz' or 'rubygems-2.0.3.tgz', it's not possible to validate it.
If you wish to continue with unverified download add '--verify-downloads 1' after the command.

There has been an error while trying to fetch the source. 
Halting the installation.
Ricks-MacBook-Pro:~ rickthomas$ 

I just got the same error using gcc 4.7.2 from homebrew via

export CC=gcc-4.7
export GCC=usr/local/Cellar/gcc/4.7.2/bin
added GCC to my PATH

Did you resolve this? --verify-downloads 1 works?

$ gem install rubygems

ERROR:  Your gem push credentials file located at:

    /Users/kmandrup/.gem/credentials

has file permissions of 0644 but 0600 is required.

Fixed with a simple:

$ chmod 0600 /Users/kmandrup/.gem/credentials

Now I'm trying

$ rvm use 2.0.0
$ gem install rubygems

ERROR:  Could not find a valid gem 'rubygems' (>= 0), here is why:
          Unable to download data from http://rubygems.org/ - too many connection resets (http://production.s3.rubygems.org/latest_specs.4.8.gz)

Damn!

First I downloaded rubygems as a zip file, then moved the unpacked rubygems-2.0.3 folder into my ruby 2.0.0-p0 /gems folder. Then, it looks like https is now required for rubygems access.

$ gem env remotesources
http://rubygems.org/
kmandrup:~ $ subl ~/.gemrc
kmandrup:~ $ subl /etc/gemrc
kmandrup:~ $ gem sources -r http://rubygems.org/
http://rubygems.org/ removed from sources
kmandrup:~ $ gem sources -a https://rubygems.org/
https://rubygems.org/ added to sources
kmandrup:~ $ gem install bundler
Fetching: bundler-1.3.2.gem (100%)
Successfully installed bundler-1.3.2
Done installing documentation for bundler (0 sec).
1 gem installed

Sweet :)