Nintendo has announced it will reveal it's next console, codenamed "Revolution" at E3 in 2005. Sony and MS will likely do the same, with all three coming out late 2005 or 2006.
Microsoft is expected to launch its Xbox 2 console in fall 2005, and Sony is expected to bring its PlayStation 3 game hardware to market in 2006 alongside Nintendo's. It's also expected that Microsoft and Sony will release Xbox2/PS3 PC-hybrids after the launch of the console versions.