I'm using IDEA 5.1 and currently run it with Java 6 b72. Subpixel anti-aliasing is nice... where it's visible. Running under the system look-and-feel, in this case Windows XP, standard Swing components have the nice text, but custom components, such as the editor (but there are many others), aren't anti-aliased in this way, which is a shame.
The custom look-and-feels, such as Alloy, which obviously render their own text, seem to be even less "subpixel-AA-friendly".
To add support for this, see:
Note that this is backwards-compatible, and the call won't fail under Java 1.4.2. It just won't do anything... But for those on the bleeding edge (which will eventually become everyone), it'd be very nice and stop a lot of subpixel-AA FUD in IDE comparisons.