I have hacked together a replacement for the long-missing Lua get_aa() function, that gets the amino acid type for a segment.
Download the code here: http://fold.it/portal/recipe/3779
When this script is run, it prints out the amino acid sequence. Compare to the Show Alignment tool.
The trick to getting it to work is the get_segment_score_part('reference', i) function. This turns out to return a unique, unvarying, number for each amino acid type. With a little lookup table, I am able to retrieve which kind of amino acid the segment is.
The code also has a function IsHydrophobic() that returns whether a segment is hydrophobic or not.