In-Game Text Chatting
Some games, like Media Molecule's "Little Big Planet," allow for chatting during play. Simply press the square button and an on-screen keyboard will appear, allowing you to enter your messages.
In-Game Chat Rooms
Players can start or join chat rooms with their friends, either while playing a game or not. This option is under the "Friends" tab of the PS3's main menu.
Voice Chat
Some games, like "Warhawk," support the use of voice chat (with a wireless headset) so gamers can talk to their friends or opponents online.
PlayStation Home
PlayStation Home, which serves as the primary PS3 online community, supports both text (with the square button) and voice chat (with the wireless headset).
Controller Keyboard
Wireless keyboards are available that connect directly to the PS3 controller. This can make in-game chatting much easier.