Hi

it's funny how quickly you vote against BibTeX, but at least it is a 
format that is frequently used in the wild to create citations. If you 
call BibTeX undocumented and garbage then how do you call MARC which is 
far more difficult to make use of?

My assumption was that there is a specific use case for bibliographic 
data in twitter annotations:

I. Identifiy publication => this can *only* be done seriously with 
identifiers like ISBN, DOI, OCLCNum, LCCN etc.

II. Deliver a citation => use a citation-oriented format (BibTeX, CSL, RIS)

I was not voting explicitly for BibTeX but at least there is a large 
community that can make use of it. I strongly favour CSL 
(http://citationstyles.org/) because:

- there is a JavaScript CSL-Processor. JavaScript is kind of a 
punishment but it is the natural environment for the Web 2.0 Mashup 
crowd that is going to implement applications that use Twitter annotations

- there are dozens of CSL citation styles so you can display a citation 
in any way you want

As Ross pointed out RIS would be an option too, but I miss the easy open 
source tools that use RIS to create citations from RIS data.

Any other relevant format that I know (Bibont, MODS, MARC etc.) does not 
aim at identification or citation at the first place but tries to model 
the full variety of bibliographic metadata. If your use case is

III. Provide semantic properties and connections of a publication

Then you should look at the Bibliographic Ontology. But III does *not* 
"just subsume" usecase II. - it is a different story that is not beeing 
told by normal people but only but metadata experts, semantic web gurus, 
library system developers etc. (I would count me to this groups). If you 
want such complex data then you should use other systems but Twitter for 
data exchange anyway.

A list of CSL metadata fields can be found at

http://citationstyles.org/downloads/specification.html#appendices

and the JavaScript-Processor (which is also used in Zotero) provides 
more information for developers: http://groups.google.com/group/citeproc-js

Cheers
Jakob

P.S: An example of a CSL record from the JavaScript client:

{
"title": "True Crime Radio and Listener Disenchantment with Network 
Broadcasting, 1935-1946",
   "author": [ {
     "family": "Razlogova",
     "given": "Elena"
   } ],
  "container-title": "American Quarterly",
  "volume": "58",
  "page": "137-158",
  "issued": { "date-parts": [ [2006, 3] ] },
  "type": "article-journal"
}


-- 
Jakob Voß <[log in to unmask]>, skype: nichtich
Verbundzentrale des GBV (VZG) / Common Library Network
Platz der Goettinger Sieben 1, 37073 Göttingen, Germany
+49 (0)551 39-10242, http://www.gbv.de