Ruby

Deploy:

Optimizing resource usage

http://weblog.textdrive.com/article/175/rails-optimizing-resource-usage

Scaling Rails

http://railslab.newrelic.com/scaling-rails
http://www.infoq.com/articles/gregg-pollack-scaling-rails

MySql driver deficiencies makes Mongrel and WEBrick to hang

http://railsforum.com/viewtopic.php?id=3038
http://www.mail-archive.com/[e-mail]/msg00133.html

About gems

Authlogic
Mechanize

CMS

This seems interesting as long as is multi-lingual by default, not as Radius: http://zenadmin.org/en

Reference guides

http://www.techotopia.com/index.php/Ruby_Essentials
No need to mention rail's API: http://api.rubyonrails.org/

Adhearsion, an Asterisk framework

RubyFringe talk: http://www.infoq.com/interviews/phillips-adhearson-voip

Ruby for SymbyanOS

Take a look at: https://developer.symbian.com/main/community/open_source_projects/ruby/index.jsp