Like others have said, Nintendo has claimed that the Wii will retail at about $250 US. They are also HIGHLY likely to reveal launch dates and price plans for the Virtual Console system, as well as other games and developments for the rest of the year. I know I'll have my computer camped out at several gaming sites, eagerly awaiting Wednesday/Thursday's news.
Speculations:
Cost of Wii: $200-250
Launch Date: Before the PS3's US release date, November 17, 2006
Games: $40-60
Virtual Console: NES ($2), SNES ($5), N64 ($7-10), SEGA ($5-10). No info on a monthly subscription.
Other:
-Around 20 games at Wii's launch, including LoZ: Twilight Princess, Metroid Prime 3, Elebits, Wii Sports, Red Steel, and many more.
-Some games might be bundled with free Virtual Console games, most likely based around the purchased game (ex: Metroid Prime 3 would most likely have NES Metroid).
-The console will most likely be available in Black or White. Controller color schemes are unannounced. I'm personally hoping for a skin line like the 360 faceplates...
Anything I'm forgetting, let me know. The console comes with a Wii-mote and (I think) the analog attachment.