The requested URL /node was not found on this server I am setting up Drupal locally in my Ubuntu. 
I used drush to download and install Drupal 7. (using mysqladmin to create the database and the user)

All worked well, I have the default homepage, but when I try to do any action (logging in, registering) I get a 404. I imagine the mod_rewrite doesn't work..

I installed the Apache module and enabled it, restarted the server, but no lack... 

I am guessing mod_rewrite needs more parameterization...?

update: I can access correctly the page with this url: 

http://localhost/index.php?q=user


so I guess my mod_rewrite clearly doesn't work as it should..
Have you verified that the .htaccess file from the Drupal 7 core package is in the website root?

You can easily download and extract that file from drupal.org base package:  http://drupal.org/project/drupal