[AUTOMATIC UPDATE]
$ ./drush pm install views-6.x-2.0-alpha1
Project views successfully installed (version 6.x-2.0-alpha1).
$ head -n2 modules/views/views.module 
<?php
// $Id: views.module,v 1.218 2008/02/17 02:22:33 merlinofchaos Exp $
[ENABLE MODULE]
$ ./drush pm refresh
Refreshing update status information ...
Done.
$ ./drush pm update
Update information last refreshed: Sat, 10/11/2008 - 21:56

Update status information on all installed and enabled Drupal modules:
  Name                          	Installed version	Recommended version	Status          
  ----                          	-----------------	-------------------	------
  Admin Role                    	6.x-1.0-beta2    	6.x-1.0-beta2      	OK              
  Drupal                        	6.5              	6.5                	OK              
  Content Construction Kit (CCK)	6.x-2.0-rc10     	6.x-2.0-rc10       	OK              
  CVS deploy                    	6.x-1.0          	6.x-1.0            	OK              
  Drush                         	6.x-1.1          	6.x-1.1            	OK              
  Link                          	6.x-1.x-dev      	6.x-1.x-dev        	OK              
  Views                         	6.x-2.0-alpha1   	6.x-2.0-rc5        	Update available

Updates will be made to the following projects:
Views [views-6.x-2.0-rc5]

Note: Updated modules can potentially break your site. It's not recommended to update production sites without prior testing.
Note: A backup of your package will be stored to backups directory if no .svn directory is found.
Note: If you have made any modifications to any file that belongs to one of these projects, you will have to migrate those modifications after updating.
Do you really want to continue? (y/n): y
Project views was updated successfully. Installed version is now 6.x-2.0-rc5.
Backups were saved into the directory /home/owen/workspace/drupal-6//backup/modules/20081011215706.
You should now run update.php through your browser.
$ head -n2 modules/views/views.module 
<?php
// $Id: views.module,v 1.314 2008/10/08 19:05:02 merlinofchaos Exp $

[USER-SPECIFIED VERSION UPDATE]
$ rm -rf modules/views/
$ ./drush pm refresh
Refreshing update status information ...
Done.
$ ./drush pm install views-6.x-2.0-alpha1
Project views successfully installed (version 6.x-2.0-alpha1).
$ ./drush pm refresh
Refreshing update status information ...
Done.
$ ./drush pm update views-6.x-2.0-alpha2
Update information last refreshed: Sat, 10/11/2008 - 21:59

Update status information on all installed and enabled Drupal modules:
  Name                          	Installed version	Recommended version	Status                     
  ----                          	-----------------	-------------------	------
  Admin Role                    	6.x-1.0-beta2    	6.x-1.0-beta2      	OK                         
  Drupal                        	6.5              	6.5                	OK                         
  Content Construction Kit (CCK)	6.x-2.0-rc10     	6.x-2.0-rc10       	OK                         
  CVS deploy                    	6.x-1.0          	6.x-1.0            	OK                         
  Drush                         	6.x-1.1          	6.x-1.1            	OK                         
  Link                          	6.x-1.x-dev      	6.x-1.x-dev        	OK                         
  Views                         	6.x-2.0-alpha1   	6.x-2.0-alpha2     	Specified version available

Updates will be made to the following projects:
Views [views-6.x-2.0-alpha2]

Note: Updated modules can potentially break your site. It's not recommended to update production sites without prior testing.
Note: A backup of your package will be stored to backups directory if no .svn directory is found.
Note: If you have made any modifications to any file that belongs to one of these projects, you will have to migrate those modifications after updating.
Do you really want to continue? (y/n): y
Project views was updated successfully. Installed version is now 6.x-2.0-alpha2.
Backups were saved into the directory /home/owen/workspace/drupal-6//backup/modules/20081011220022.
You should now run update.php through your browser.
$ head -n2 modules/views/views.module 
<?php
// $Id: views.module,v 1.219 2008/02/18 00:25:07 merlinofchaos Exp $