Merged Ruby Packages Of Debian Are Now Available
Merged Ruby packages of Debian [Version: 1.8.2-3] has come to the testing release after some discussions . Many Ruby libraries are now included in libruby1.8, which ruby1.8 depends on. So you can install most Ruby environment (the interpreter and the most libraries) by sudo apt-get install ruby1.8. Most users will be happy with this single command!
It makes it easier to install Ruby in Debian, however, the upstream—original, standard—Ruby are still separated into a few packages because of maintenance and so forth. If you need Tcl/Tk you need to install libtcltk-ruby1.8; if you need openssl you have to install libopenssl-ruby1.8 one by one. You can see the other packages here.
1 A new package like ruby1.8-bundle that contains all Ruby environment seems to be planned but is not available yet.