While I would certainly find it disturbing to see my Yahoo avatar get raped by Pikachu, it's unlikely that I would feel personally harassed by witnessing a digital depiction of the act, even if it did involve an online representation of myself.
Some, however, invest a greater deal of time, effort and emotion into their virtual counterparts and live alternate lives through them, thus feeling personally wronged when their avatars are virtually violated. They may be hardcore gamers who find friends playing MMORPGs, social networkers who find love on online dating sims, or even entrepreneurs who make a living in virtual marketplaces.
RA 8353 limits rape to the physical act of carnal knowledge, which makes "virtual rape" impossible. This definition places forced sexual acts through text or animation in chatrooms, massively multiplayer online games, etc., outside said RA, which makes sense. While such acts would certainly merit harassment charges or civil damages, I would think it unfair to place a virtual rape victim in the same position as a real-world rape victim--It just isn't the same.
Sexual deviants should note however, that just because it isn't punishable by reclusion perpetua, doesn't mean they have a license to be an ass online.