Getting sqlite3 to work with ruby and centos5 is apparently something of a chore.
The notes below are the collected notes regarding how to get it to work. The instructions appear to allow the sqlite ruby gem to be successfully installed.
Installing ruby and ruby gems on CentOS 5:
#yum install ruby
#yum install ruby-devel ruby-gems
[And the most important/non-obvious one: yum install sqlite-devel]
#yum install sqlite-devel
#gem install sqlite3-ruby
Note: after installing the sqlite3-ruby as a ruby gem, your ruby code will have to include the following in order to use the sqlite3 gem: