This new release includes the ability to add, delete, and query contacts. You can also submit arbitrary s-expression queries to Evolution, like this:

[tom@hal revolution]$ irb
irb(main):001:0gt; require 'rubygems'
irb(main):002:0gt; require_gem 'revolution'
irb(main):003:0gt; rev = Revolution::Revolution.new
irb(main):004:0gt; rev.get_contacts_with_query(" contains 'full_name' 'Copeland')").each {|c| puts c.first_name }
Madelyn
Lee
Alina
Dave