OK, I've had a few days to think about this. Here are some thoughts:
1. In my copy of Bookends 11, at least, the highlighted fields for Conference proceedings are Authors, Title, Date, Key (all expected), and Conf Name. If the Proceedings volume is essentially a book, why aren't the Volume and the Pages fields highlighted instead of Conf Name? If I fill in the fields as expected, but also add pages, I get APA 5th output like this:
Pals, T. (2009). Simple solutions: Creating interactive websites with drag and drop WizzyWigs. Paper presented at the Thirteenth Annual JALT CALL SIG Conference 2008.
To my mind, this is almost a suitable format for a conference paper that hasn't been published in a Proceedings volume, and therefore the Type could perhaps be better named as "Unpublished conference paper" or similar? The remaining problem is with dates. The 2008 is there because I included it in the conference name (because it's part of the title of the proceedings volume). The (2009) bit (the date of publication of the volume) is meaningless, which implies that the date field should be used for the date of the presentation (or the date range of the conference as a whole)?
2. If I use the same example as above, but input the proceedings volume info first as an edited book, and then use the Replicate as Book Chapter function, I get the following:
Pals, T. (2009). Simple solutions: Creating interactive websites with drag and drop WizzyWigs. In M. Thomas (Ed.), New frontiers in CALL: Negotiating diversity: Selected proceedings of the thirteenth annual JALT CALL SIG conference 2008. JALT CALL SIG.
I believe that's exactly the right format for this kind of item. And that would imply that we don't actually need any Proceedings Types as such (either for individual papers or for volumes) but that it's unpublished papers and presentations that are the real issue.
3. I suspect that these days it's quite common to cite conference papers that have not been formally published but whose text is available online because the presenter has uploaded it.The APA 6th guide gives such an example, but where the abstract only is available online:
Liu, S. (2005, May). Defending against business crises with the help of intelligent agent based early warning solutions. Paper presented at the Seventh International Conference on Enterprise Information Systems, Miami, FL. Abstract retrieved from
http://www.iceis.org/iceis2005/abstracts_2005.htm
Presumably, the "Abstract retrieved" bit would become simply "Retrieved" if the whole paper were downloadable.
It's not entirely clear what to do with these. One could use Internet, or, probably better, Conference proceedings (and add the "retrieved" bit oneself). To my mind, this is such a common type that it would be good to have it in Bookends by default; but perhaps I'm wrong about this, and it's really an edge case?
4. The example I've put in point 1 above, if I switch the format to APA 6th, becomes:
Pals, T. (2009, Simple solutions: Creating interactive websites with drag and drop WizzyWigs. Paper presented at the Thirteenth Annual JALT CALL SIG Conference 2008.
The APA 6th formats are all new so presumably still need some polishing.
5. Using the example in point 1 again, I notice that Replicate as Book Chapter is available. When I use it, the presentation/proceedings chapter title becomes the title of the proceedings volume. To me, this suggests systematic ambiguity within Bookends as to whether Conference proceedings represents the whole conference (volume) or a part (presentation or paper) of the conference (volume).
6. BibTeX has @Proceedings and @Inproceedings as Types, but they're both mapped on to Conference proceedings in Bookends.
All the examples I've given are in APA formats, but I think there are some valid general points here, at least pertaining to nomenclature and possible enhancements to the User Guide if nothing else. Any thoughts, anyone?