Facebook unveiled a rival to RIM's BBM and Apple's iMessage yesterday with the announcement of Facebook Messenger. The free app (available now for both iOS and Android devices) allows you to send and receive instant messages from your Facebook friends or mobile contacts. Allowing you to see your previous chats and chat transcripts, you can jump back into a conversation or start a new one with a single person or a group. You can even send photos, plan events on the fly, and rename chat logs on the go.
Another feature allows you to disconnect for a period of time — you can delay incoming message alerts for an hour, or until 8 a.m. the next day so you can get a restful night's sleep. Additionally, you can set alert parameters for each chat, prioritizing which alerts you receive, and which ones you don't.
Get a closer look at some screenshots of Facebook Messenger in the gallery!