Impressionnant ce presto :
# yum update

Loaded plugins: fastestmirror, presto, refresh-packagekit
Setting up Update Process                                
Resolving Dependencies                                   
--> Running transaction check                            
---> Package PyKDE4.i686 0:4.3.4-1.fc12 set to be updated
---> Package kde-l10n.noarch 0:4.3.4-1.fc12 set to be updated             
---> Package kde-l10n-French.noarch 0:4.3.4-1.fc12 set to be updated      
---> Package kde-settings.noarch 0:4.3-15.1 set to be updated             
---> Package kde-settings-kdm.noarch 0:4.3-15.1 set to be updated         
   ...                
--> Finished Dependency Resolution                                                 

Dependencies Resolved

===================================================================================
 Package                         Arch   Version                      Repository    
                                                                              Size 
===================================================================================
Updating:                                                                          
 PyKDE4                          i686   4.3.4-1.fc12                 updates 3.0 M 
 kde-l10n                        noarch 4.3.4-1.fc12                 updates  13 k 
 kde-settings                    noarch 4.3-15.1                     updates  41 k 
 kde-settings-kdm                noarch 4.3-15.1                     updates  27 k 
 kdeaccessibility                i686   1:4.3.4-1.fc12               updates 6.1 M 
 kdeaccessibility-libs           i686   1:4.3.4-1.fc12               updates  62 k 
 kdeartwork-kxs                  i686   4.3.4-1.fc12                 updates  60 k 
 kdeartwork-screensavers         i686   4.3.4-1.fc12                 updates 655 k 
 kdebase                         i686   6:4.3.4-1.fc12               updates 4.6 M 
   ...

Transaction Summary
===================================================================================
Install       3 Package(s)                                                         
Upgrade      59 Package(s)                                                         

Total download size: 193 M
Is this ok [y/N]: y       
Downloading Packages:     
Setting up and reading Presto delta metadata
updates/prestodelta                                         | 306 kB     00:01     
Processing delta metadata                                                          
Download delta size: 20 M                                                          
(1/49): PyKDE4-4.3.3-4.fc12_4.3.4-1.fc12.i686.drpm          | 464 kB     00:02     
   ...    
(10/49): kdebase-4.3.3-3.fc12_4.3.4-1.fc12.i686.drpm        | 696 kB     00:02     
(12/49): kdebase-runtime-4.3.3-5.fc12_4.3.4-2.fc12.i686.drp | 856 kB     00:03      
(16/49): kdegames-4.3.3-2.fc12_4.3.4-1.fc12.i686.drpm       | 2.6 MB     00:13      
(18/49): kdegraphics-4.3.3-1.fc12_4.3.4-1.fc12.i686.drpm    | 688 kB     00:03    
(20/49): kdelibs-4.3.3-4.fc12_4.3.4-3.fc12.i686.drpm        | 1.2 MB     00:05     
(21/49): kdelibs-common-4.3.3-4.fc12_4.3.4-3.fc12.i686.drpm |  46 kB     00:00     
(22/49): kdelibs-experimental-4.3.3-1.fc12_4.3.4-1.fc12.i68 | 5.4 kB     00:00     
(23/49): kdemultimedia-4.3.3-2.fc12_4.3.4-1.fc12.i686.drpm  | 598 kB     00:02     
(24/49): kdemultimedia-libs-4.3.3-2.fc12_4.3.4-1.fc12.i686. |  14 kB     00:00     
(25/49): kdenetwork-4.3.3-5.fc12_4.3.4-1.fc12.i686.drpm     | 990 kB     00:04     
   ...   
(49/49): xdg-utils-1.0.2-14.20091016cvs.fc12_1.0.2-16.20091 |  11 kB     00:00     
Finishing rebuild of rpms, from deltarpms                                          
<delta rebuild>                                             | 178 MB     02:43     
Presto reduced the update size by 89% (from 178 M to 20 M).                        
Package(s) data still to download: 15 M                                            
(1/13): kde-l10n-4.3.4-1.fc12.noarch.rpm                    |  13 kB     00:00     
(2/13): kde-settings-kdm-4.3-15.1.noarch.rpm                |  27 kB     00:00     
   ...
(13/13): pywebkitgtk-1.1.6-2.fc12.i686.rpm                  |  45 kB     00:00     
-----------------------------------------------------------------------------------
Total                                              130 kB/s |  15 MB     01:58     
Running rpm_check_debug                                                            
Running Transaction Test                                                           
Finished Transaction Test                                                          
Transaction Test Succeeded                                                         
Running Transaction                                                                
  Updating       : oxygen-icon-theme-4.3.4-1.fc12.noarch                     1/121 
  Updating       : kde-settings-4.3-15.1.noarch                              2/121 
  Updating       : 6:kdelibs-common-4.3.4-3.fc12.i686                        3/121 
   ...

Complete!
Tout KDE mis à jour en téléchargeant 35 MB (au lieu de 193 MB) !