Capcom will be releasing some new content for Mega Man 9 this week. Endless Attack is the first of the new additions which is an infinite length level which challenges you to see how far you can get. The other is Proto Man which will allow you to play the game as Proto Man (ironically!).
Proto Man has different abilities to Mega Man and will be able to deflect bullets, take double damage and has a double bounce back when he has been hit.
The update arrives on US shores today with the WiiWare update (Europe should get it Friday), while the XBLA content arrives tomrrow and the PSN update by Thursday.