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.
I understand there are some changes, but the samples should work!, and the serial port is basic.
What is "not working" about Serial.println()? Not compiling? Not running? Not printing anything on the serial output?
The problem compiles and uploads OK but I am not receiving anything thrugh the serial port (usb). The same program compiled with 0022 works ok.
My program started when I tried to get working this display: http://dx.com/p/jy-mcu-16x-digital-tube-yellow-led-module-104311?utm_rid=68099021&utm_source=affiliate
with this library:http://code.google.com/p/tm1638-library/
that claims it is compatible with Arduino 1.0 since many versions.
When uploaded the small sample program included with the library I found random leds displayed, then I tried to debug the app inserting some Serial.println, but I received nothing in the serial monitor. Then I inserted a Serial.println at setup function and when it didn't work (sent nothing, no tx/rx leds blinking, etc.). Then I tried uploading the ascii table example of Arduino IDE and it sent nothing through serial port.
My next step was installing Arduino 0022 and all the programa (ascii table and display library worked well).
I must say that some months ago, I had similar problems with Arduino 1.0 and Arduino ISP (it only worked with Arduino 0022).