With gem dependency it is possible to check the dependencies for your gem before you install it.
Here is an example output for Nokogiri:
Gem nokogiri-1.4.4
hoe (>= 2.6.2, development)
minitest (>= 1.6.0, development)
racc (>= 0, development)
rake-compiler (>= 0, development)
rexical (>= 0, development)
rubyforge (>= 2.0.4, development)
Posted by Kim Klotz to makandra dev (2011-07-14 15:10)