IDE v1.0.1 is working great for me in Ubuntu v11.10 and v12.04 with a Mega 2560. I noticed there have been a few format and data type changes when porting from v0022 to v1.0.1.
What is "not working" about Serial.println()? Not compiling? Not running? Not printing anything on the serial output?
If you post your sketch, maybe I could provide a more exact answer.