pre in lists

[Boris Le Ninivin]

When I try to use the code block syntax in a list, i.e :

1. some text
2. some code :
     My first line of code
     The second one
         Some indented code
         Another line
3. end of the list

it doesn't work. Yet it appears that the syntax is valid (I checked on 
the w3 validator). I would need that functionality. Would it be possible 
to improve the markdown parser by adding it ?

Thanks.