The Twitterverse is buzzing with are-they-or-aren't-they-back-together speculation after Rihanna and ex-boyfriend Chris Brown released two tracks on which they both appear.

The two singles were unleashed on the Internet Monday and instantly sparked a virtual backlash, with many accusing Rihanna of condoning domestic violence for working with the man who was convicted of assaulting her.

Brown was sentenced to five years' probation after he admitted to beating Rihanna in 2009 on the night before the Grammy Awards.

While the two have not indicated that they are once again a couple, Brown can be heard singing on a remix of Rihanna's "Birthday Cake," while she appears on a remix of his "Turn Up the Music."

On Monday, Brown tweeted a link to his song, which Rihanna later re-tweeted. She also tweeted the "Birthday Cake" remix.