Reboundfinder searches twitter for twits that have anounced that they have been dumped (sudden unilateral separation, to be more precise) by their significant other. Then followers of this bot can discover the newly broken-hearted.
From the name of the bot, it seems that its target audience is singles looking for new singles to date. For its followers, it might be advantageous of them to prey on someone on the "rebound"; to experience the benefits of a romantic relationship and dodge the negative parts. It somewhat quickens the life-course of post-breakup, as the time to reflect on past relationships disappears since the person will be offered many blind dates after such an announcement.
Another use for this could be finding others and forming a synchronic community to cope with breakup.