Recently I had to install the Subversive plug-in in Flash Builder 4, but was unable to due to consistent errors during installation.

FlashBuilder -> Help -> Install new Software http://download.eclipse.org/technology/subversive/0.7/update-site/

I’m not sure if this is a bug in FlashBuilder 4, but this link just was just giving me errors during installation. If you are also having this problem, you can try another location that worked for me:

http://download.eclipse.org/releases/galileo/

thanks to http://www.flex-tutorial.fr/2010/03/30/flash-builder-4-installation-de-subversive-et-connecteurs-svn/ for the tip