I'm trying out jEdit on Windows and also experiencing poor font smoothing, at least compared to what I'm used to. Not sure if this will come across the same on all monitors, but I thought I'd take a few screenshots comparing font smoothing in jEdit to Wordpad (i.e. how fonts look in most editors when ClearType is enabled):

Wordpad & others (ClearType): http://img3.imageshack.us/img3/3316/wordpadcleartype5rc.png
jEdit (smooth text): http://img3.imageshack.us/img3/2466/jeditsmoothing8ci.png
jEdit (fractional font smoothing): http://img3.imageshack.us/img3/718/jeditfractional3pr.png

Is it visible from the pictures, or not? Not quite sure how to describe the way fonts in jEdit look on my LCD monitor except to say that they don't look very good at all. I tried the "-Dswing.aatext=true" switch suggested above, and it just made the interface fonts look "muddy" without affecting the text area:

http://img3.imageshack.us/img3/4111/jeditswingaatext9pn.png

I don't think jEdit supports ClearType directly, but you can enable Java font smoothing by passing the parameter -Dswing.aatext=true to the Java virtual machine (JVM) when jEdit starts up. Change your jEdit shortcut(s) to something like the following:

"C:\Program Files\Java\jre1.5.0_04\bin\javaw.exe" -Dswing.aatext=true -jar "C:\Program Files\jEdit\jedit.jar"

You may have different directories for your JVM and jEdit installation. The double quotes are needed in this example because the paths to the javaw.exe and jedit.jar executable files contain spaces. Hope this helps!