mikutter (http://mikutter.hachune.net/) won't work after update of Ruby to 2.0 on Arch linux (or others), then update libraries with gem. For specific, read this article.

mikutter-ruby2.0.howto

Mikutter, the moest twitter client wasn't launched with such error after I updated my Arch repositories.
11:32% ruby mikutter.rb
/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require': /usr/lib/ruby/vendor_ruby/2.0.0/x86_64-linux/pango.so: undefined symbol: rb_cCairo_Context - /usr/lib/ruby/vendor_ruby/2.0.0/x86_64-linux/pango.so (LoadError)
	from /usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'
	from /usr/lib/ruby/vendor_ruby/2.0.0/pango.rb:28:in `rescue in <top (required)>'
	from /usr/lib/ruby/vendor_ruby/2.0.0/pango.rb:24:in `<top (required)>'
:
:
:
:

Then, I made the commands below, and it made mikutter to work easily.
So, they are this.
% gem update && gem install memoize typed-array addressable  oauth pango bsearch

evidence is here.

vimshell% gem update
Updating installed gems
Updating minitest
!!!WARNING:  You don't have /home/iorivur/.gem/ruby/2.0.0/bin in your PATH,!!!
!!!	  gem executables will not run.!!!
Fetching: minitest-4.7.0.gem (100%)
Successfully installed minitest-4.7.0
Parsing documentation for minitest-4.7.0
Installing ri documentation for minitest-4.7.0
Installing darkfish documentation for minitest-4.7.0
Done installing documentation for minitest (3 sec).
Updating rake
Fetching: rake-10.0.4.gem (100%)
Successfully installed rake-10.0.4
Parsing documentation for rake-10.0.4
Installing ri documentation for rake-10.0.4
Installing darkfish documentation for rake-10.0.4
Done installing documentation for rake (8 sec).
Updating test-unit
Fetching: test-unit-2.5.4.gem (100%)
Successfully installed test-unit-2.5.4
Parsing documentation for test-unit-2.5.4
Installing ri documentation for test-unit-2.5.4
Installing darkfish documentation for test-unit-2.5.4
Done installing documentation for test-unit (7 sec).
Gems updated: minitest rake test-unit
vimshell% gem install memoize typed-array addressable  oauth pango bsearch
!!!WARNING:  You don't have /home/iorivur/.gem/ruby/2.0.0/bin in your PATH,!!!
!!!	  gem executables will not run.!!!
Fetching: memoize-1.3.1.gem (100%)
Successfully installed memoize-1.3.1
Parsing documentation for memoize-1.3.1
Installing ri documentation for memoize-1.3.1
Done installing documentation for memoize (0 sec).
Fetching: typed-array-0.1.2.gem (100%)
Successfully installed typed-array-0.1.2
Parsing documentation for typed-array-0.1.2
Installing ri documentation for typed-array-0.1.2
Done installing documentation for typed-array (0 sec).
Fetching: addressable-2.3.3.gem (100%)
Successfully installed addressable-2.3.3
Parsing documentation for addressable-2.3.3
Installing ri documentation for addressable-2.3.3
Done installing documentation for addressable (1 sec).
Fetching: oauth-0.4.7.gem (100%)
Successfully installed oauth-0.4.7
Parsing documentation for oauth-0.4.7
Installing ri documentation for oauth-0.4.7
Done installing documentation for oauth (1 sec).
Fetching: pkg-config-1.1.4.gem (100%)
Successfully installed pkg-config-1.1.4
Fetching: cairo-1.12.4.gem (100%)
Building native extensions.  This could take a while...
Successfully installed cairo-1.12.4
Fetching: glib2-1.2.4.gem (100%)
Building native extensions.  This could take a while...
Successfully installed glib2-1.2.4
Fetching: pango-1.2.4.gem (100%)
Building native extensions.  This could take a while...
Successfully installed pango-1.2.4
Parsing documentation for pkg-config-1.1.4
!!!unable to convert "\xDB" from ASCII-8BIT to UTF-8 for lib/cairo.so, skipping!!!
!!!!!!Installing ri documentation for pkg-config-1.1.4
Parsing documentation for cairo-1.12.4
!!!unable to convert "\xD0" from ASCII-8BIT to UTF-8 for lib/glib2.so, skipping!!!
!!!!!!Installing ri documentation for cairo-1.12.4
Parsing documentation for glib2-1.2.4
!!!unable to convert "\x9F" from ASCII-8BIT to UTF-8 for lib/pango.so, skipping!!!
!!!!!!Installing ri documentation for glib2-1.2.4
Parsing documentation for pango-1.2.4
Installing ri documentation for pango-1.2.4
Done installing documentation for pkg-config, cairo, glib2, pango (2 sec).
Fetching: bsearch-1.5.0.gem (100%)
Successfully installed bsearch-1.5.0
Parsing documentation for bsearch-1.5.0
Installing ri documentation for bsearch-1.5.0
Done installing documentation for bsearch (0 sec).
9 gems installed

11:37% mikutter
/home/iorivur/.gem/ruby/2.0.0/gems/cairo-1.12.4/lib/cairo.rb:152: warning: already initialized constant Cairo::WIN32Surface
/usr/lib/ruby/vendor_ruby/2.0.0/cairo.rb:152: warning: previous definition of WIN32Surface was here
/opt/mikutter/core/plugin/display_requirements/display_requirements.rb:5: warning: already initialized constant CACHE_DIR
/opt/mikutter/core/plugin/aspectframe/aspectframe.rb:12: warning: previous definition of CACHE_DIR was here
gui_pane_join_window :default, :default
gui_pane_join_window :"__Plugin::GUI::Pane_20489_50ff5a0f_26114644", :default
/opt/mikutter/core/plugin/gtk/gtk.rb: line 377
   Gtk-CRITICAL **:IA__gtk_window_set_focus: assertion `gtk_widget_get_can_focus (focus)' failed


And now it works!