Indulgences are one of the Church's oldest traditions and allows believers to gain forgiveness and spend less time in purgatory and is usually gained through acts of faith.
However a leading Cardinal has said that for those who cannot make it to see the Pontiff in person can use "the new means of social communication" instead.
The faithful who are legitimately impeded [from attending] can obtain the plenary indulgence if [...] they follow these same rites and pious exercises [...] always with appropriate devotion, by the new means of social communication.
However simply following the Pope's Twitter feed may not be enough and believers keen to make use of the online indulgences the posts must see them, "bear authentic spiritual fruit in the hearts of each one of us."
Be aware. You don't get the indulgence the way you get a coffee from a vending machine. There's no counter handing out certificates. To put it another way, it won't be sufficient to attend the mass in Rio online, follow the Pope on your iPad or visit Pope2You.net. These are only tools that are available to believers. What really matters is that the Pope's tweets from Brazil, or the photos of World Youth Day that will be posted on Pinterest, should bear authentic spiritual fruit in the hearts of each one of us. Then even a youngster who is a very long way from Brazil and feels involved by a video, a simple text message or an email will be truly taking part in the World Youth Day and will receive the gift of the indulgence.