Centos ruby 1.8.7 repository

With yum-utils installed, repoquery will provide the information you seek (here 'epel' being the repository).

$ repoquery -i cherokee

Name        : cherokee
Version     : 0.99.49
Release     : 1.el5
Architecture: i386
Size        : 8495964
Packager    : Fedora Project
Group       : Applications/Internet
URL         : http://www.cherokee-project.com/
Repository  : epel
Summary     : Flexible and Fast Webserver
Description :
Cherokee is a very fast, flexible and easy to configure Web Server. It supports
the widespread technologies nowadays: FastCGI, SCGI, PHP, CGI, TLS and SSL
encrypted connections, Virtual hosts, Authentication, on the fly encoding,
Apache compatible log files, and much more.

As Jeff made me notice that Ruby 1.8.7 has not been backported yet, the other only solution that comes to my mind is to use the PPA of the team packaging Ruby.

There you can find both Ruby version 1.8.7.22 and version 1.9.0.2, should you prefer.

If you don't know how to configure ubuntu to use a PPA, the instructions are also on the linked page (click on Not using Ubuntu 9.10 (karmic)? under the "Adding this PPA to your system" section.

Hope this helps! :)