Including 'import "md5"' in my Rantfile will generate the following errors, I get the errors with 0.5.6 and
0.5.8 with the gem install and installing the tarball from the web site:
rant: [ERROR] comparison of String with false failed
              /usr/lib/ruby/gems/1.8/gems/rant-0.5.6/lib/rant/import/nodes/signed.rb:77:in `sort!'
              /usr/lib/ruby/gems/1.8/gems/rant-0.5.6/lib/rant/import/nodes/signed.rb:77:in `signature'
              /usr/lib/ruby/gems/1.8/gems/rant-0.5.6/lib/rant/import/nodes/signed.rb:66:in `signature'
              /usr/lib/ruby/gems/1.8/gems/rant-0.5.6/lib/rant/import/nodes/signed.rb:63:in `each'
              /usr/lib/ruby/gems/1.8/gems/rant-0.5.6/lib/rant/import/nodes/signed.rb:63:in `signature'
rant: [ERROR] Task `default' fail.

I am using rant version:
[brailsmt]$ rant --version
rant 0.5.6

I am using ruby version:
[brailsmt]$ ruby --version
ruby 1.8.5 (2006-12-04 patchlevel 2) [i686-linux]

On Linux:
[brailsmt]$ uname -a
Linux localhost 2.6.18-gentoo-r6 #1 PREEMPT Thu Feb 8 23:36:29 CST 2007 i686 AMD Sempron(tm) 2200+ AuthenticAMD
GNU/Linux