Gamezine:
"Being free comes with certain advantages. Approximately 85% of PlayStation 3 gamers are online, in comparison to only 60% of Xbox 360 gamers."
Updates:
[UPDATE] - We are aware that PSN users have multiple accounts, in order to download content from regional stores, thus the percentages depend on Sony's methodology of gathering the statistics. If PSP users are also included, the percentage will be significantly reduced.