Is there any way to get XCode to render text in the editor with anti-aliasing enabled? I can't see anything in the preferences dialog that would do it.
XCode text is already anti-alaised. Check to make sure the font size is larger than specified in:
System Preferences -> Appearance.
If it is larger than that you can try this command at the command line to edit the application setting for xcode.
defaults write com.apple.xcode AppleAntiAliasingThreshold -int <font-size>
defaults write com.apple.xcode AppleSmoothFontsSizeThreshold -int <font-size>
The default code font in Xcode and Terminal is 10-point Monaco, which is traditionally not anti-aliased because there are hand-tuned bitmaps for this.
You can use the Fonts & Colors pane in the Xcode Preferences to have Xcode use whatever fonts, sizes and colors you prefer. For example, you could use 11-point Monaco or larger if you want anti-aliased text, or you could use one of a number of bitmap-only programming fonts at their native sizes if pixel-sharpness matters to you.
Personally, I rather like Courier 12 and Inconsolata 13 for coding. Courier comes with Mac OS X, while Inconsolata is a free monospaced font from Raph Levien.
Just a hint: To change the font for all categories in xcode click inside the category table, press cmd+a and double click somewhere in the category table. The changes you apply in the Fonts dialog afterwards are applied to all categories.
Hope this helped