John Trapp has more detail
here.
I haven't yet looked this over very carefully, but Laura Erickson may have correctly transcribed John Fitzpatrick's version of the leak timeline
here.
There is a slide detailing Fitz' version of the leak timeline in the video of Fitz' AOU plenary
here, about 3/4 of the way through.
Update--here's a screen capture containing that slide:

I don't know what this all means, but it does seem odd that there are apparent discrepancies on two key points:
1. Was the original Science paper officially accepted on April 25 or 26?
2. Was "news of the discovery" actually posted on a nationwide listserv on April 25, as stated in Fitz et al's Auk rebuttal to Jackson's commentary? As far as I can tell, no such news was posted on a nationwide listserv until a BIRDCHAT posting on the evening of April 27.
Here is an excerpt from Fitz et al's
Auk rebuttal (the bold font is mine):
Jackson is incorrect (p. 2) in stating that any of the project's confidants “made the information available ahead of schedule.” The remarkable fact is that the rediscovery was kept out of the public eye for 14 months by upwards of 200 individuals (researchers, volunteer searchers, donors, professional colleagues, personnel of The Nature Conservancy and the Cornell Lab of Ornithology, agency officials, family members, etc.). On the evening of 25 April 2005, an individual not involved in the search learned about it inadvertently and posted news of the discovery on a nation-wide listserv.
Jackson is incorrect in alleging that a “rapid path to publication for the Science article” (pp. 2, 8) compromised the peer-review process. Our article was fully peer-reviewed following standard editorial procedures, including requests by Science editors that reviewers act quickly. During this process, we made the video evidence available to editors and reviewers via a confidential web site. We submitted the article on 5 April and received official acceptance plus editorial and referee comments on 26 April. Coincidentally, the latter date was the same day that news of the rediscovery, accompanied by a host of inaccurate rumors, spread rapidly over the Internet following the previous evening's leak (see above). Inundated with inquiries from colleagues, the media, and the public, we nevertheless believed it inappropriate to make any announcement before the scientific article was published and the evidence made publicly available. On the afternoon of 26 April—after the paper had been accepted following normal procedures—the editorial staff at Science graciously agreed to expedite the article's publication, provided that we comply with the editorial changes required. We worked diligently to complete all revisions in time for release via Science Express on 28 April 2005. We remain indebted to the editorial staff of Science for their significant efforts in accommodating presentation of our paper immediately following its acceptance, thereby allowing open examination of the evidence essentially simultaneously with the public's learning about the discovery.
Just for the record, the following information appears on page 4 of Cornell's
original Sciencexpress paper (the bold font is mine):
Supporting Online Material www.sciencemag.org/cgi/content/full/1114103/DC1
Materials and Methods
SOM Text
Acknowledgments
Figs. S1 to S6
Movie S1
References and Notes
8 April 2005; accepted 27 April 2005
Published online 28 April 2005; 10.1126/science.1114103
Include this information when citing this paper.