I think this "feature" shouldn't be very difficult to achive. In fact, the most important things that are needed for it are already there. That's the advanced search, the possibility to select almost any number of albums from the list of results (or even from the whole collection), and the export function. Writing a playlist export template shouldn't be that hard to do, since playlists are very simple indeed.
A xspf 1.0 playlist skeleton should look like this ....
<?xml version="1.0" encoding="UTF-8"?>
<playlist version="1" xmlns="http://xspf.org/ns/0/">
<trackList>
<...>
</trackList>
</playlist>
and the exporter only needs to loop through the selected albums and fill in the data on the <...> area with chunks like this ...
<track>
<title> put song title here </title>
<location> put song path and link here </location>
</track>
m3u playlists are even more simple, since they basically need one header line (with "#EXTM3U" only) followed by a list of paths. Additional description lines (beginning with "#EXTINF") are easily added above each path too. So there is really nothing special or even magic about it.
Anything else, like fine tuning and randomizing the list by adding/removing or positioning tracks, is easily done in almost any player. So there is most likely no need to reinvent the wheel and put more things into this application that truly doesn't belong there ...
Just my two cents!
-pn