currently in doze:

D:\dev\downloads\ohai>rake install
(in D:/dev/downloads/ohai) mkdir -p pkg
WARNING: no rubyforge_project specified
WARNING: description and summary are identical
WARNING: deprecated autorequire specified
Successfully built RubyGem Name: ohai Version: 0.2.1 File: ohai-0.2.1.gem mv ohai-0.2.1.gem pkg/ohai-0.2.1.gem
sudo gem install pkg/ohai-0.2.1
'sudo' is not recognized as an internal or external command, operable program or batch file.
rake aborted!
Command failed with status (1): [sudo gem install pkg/ohai-0.2.1...]

though there are hopes of the OCI guys to get around this problem generically.
It does install to do
gem install pkg/ohai-0.2.1
by itself
so perhaps noting it in the readme would suffice.
Thanks!
-=r

The coreutils version of hostname, installed by fink, doesn't take an '-s' flag:

coolhand$ /sw/bin/hostname --help
Usage: /sw/bin/hostname [NAME]
  or:  /sw/bin/hostname OPTION
Print or set the hostname of the current system.

      --help     display this help and exit
      --version  output version information and exit

Report bugs to <bug-coreutils@gnu.org>.

The BSD version of the command does.

I changed the last part of /usr/local/lib/ruby/gems/1.8/gems/opscode-ohai-0.1.2/lib/ohai/plugins/darwin/hostname.rb to read:

fqdn from("hostname")
begin
hostname from("hostname -s") rescue
hostname fqdn.gsub(/..*/, "") end

The coreutils version of hostname, installed by fink, doesn't take an '-s' flag:

coolhand$ /sw/bin/hostname --help
Usage: /sw/bin/hostname [NAME]
  or:  /sw/bin/hostname OPTION
Print or set the hostname of the current system.

      --help     display this help and exit
      --version  output version information and exit

Report bugs to <bug-coreutils@gnu.org>.

The BSD version of the command does.

I changed the last part of /usr/local/lib/ruby/gems/1.8/gems/opscode-ohai-0.1.2/lib/ohai/plugins/darwin/hostname.rb to read:

 fqdn from("hostname")
 begin
  hostname from("hostname -s")
 rescue
  hostname fqdn.gsub(/\..*/, "")
 end

In lib/ohai/plugins/ec2.rb, has_ec2_mac? fails on vpc instances because their MAC addresses do not match the value specified.