Ilgauskas is a huge loss to the Cavs.
One of the big reasons their offense is so dangerous is Big Z's shooting. It creates spacing for the rest of the team, and opens the middle for slashers/cutters. Without Z around, the Cavs big men are all close to the hoop sorts so we'll likely see a big loss on the offensive end.
Remember last season, when Cleveland couldn't play Ben Wallace and Varejao together? They had to separate them and keep one alongside Ilgauskas and one alongside Joe Smith. This is the problem Cleveland will be facing. It'll be interesting to see if Mo Williams can help ease this, because it was a massive problem last season.
It also leaves Cleveland with only two established big men for a month. Good opportunity for Hickson and Jackson though.
I think this injury will put a lot of pressure on Cleveland's ability to hang in with Boston for the top seed over the next month. Ilgauskas is so important to that team.