Both trials require an Xbox Live Gold subscription and are expected to appear on the PlayStation Network within the next 24 hours, depending on your region.
Metal Gear Rising: Revengeance releases on Xbox 360 and PlayStation 3 on February 19. We previewed the first five missions last month, concluding that "between this and DmC, fans of third person action games are going to be well served in the early months of 2013."
EA has confirmed a Dead Space 3 release date of February 5, 2013 in North America and February 8, 2013 in Europe.
We published a Dead Space 3 single-player preview this morning.