Hi. I've also had this problem. It seems that there is a problem with 
the mysql gem documentation. However from my experience, the gem itself 
works.

Hope this helps

Guilherme Mello wrote:
> Hi,
>
> I'm trying to install the mysql module but I can't. I'm installing by
> the RubyGems... but happens the following error:
>
> Select which gem to install for your platform (
>  1. mysql 2.7.3 (mswin32)
>  2. mysql 2.7.1 (mswin32)
>  3. mysql 2.7 (ruby)
>  4. mysql 2.6 (ruby)
>  5. Skip this gem
>  6. Cancel installation
>   
>> 1
>>     
> Successfully installed mysql-2.7.3-mswin32
> Installing ri documentation for mysql-2.7.3-msw
> Installing RDoc documentation for mysql-2.7.3-m
> While generating documentation for mysql-2.7.3-
> ... MESSAGE:   Unhandled special: Special: type
> v 1.20 2006-12-20 05:31:52 tommy Exp $ -->"
> ... RDOC args: --op c:/ruby/lib/ruby/gems/1.8/d
> lude ext --main README --quiet ext README docs/
> (continuing with the rest of the installation)
>   
> ------------------------------------------------------------------------
>
>
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>