UPDATE ON THE INSCRIBED METAL PLATES: Reader Justin Kerk has referred me to a 2007 discussion on the Unicode mailing list of "Menorah- and Hebrew-inscribed lead plates of dubious provenance." These may be the plates currently in the news.
The Unicode list posts are here and here. There are two images, which can be downloaded here and here. Neither are particularly clear, although many letters and much of the decoration are visible. The text is written in the paleo-Hebrew script. The article linked to in this post has a photo of one codex of the newly reported metal plates, but it is terrible; I can't read any of the script or see any of the inscribed decorations clearly. Also, the binding is not visible. Nevertheless, it seems likely enough that the Unicode plates are from the same corpus.
We need the following for this supposed find to be shown to be a genuine collection of ancient books:
1. Publication in a scholarly journal of the metal analysis that shows the lead to be ancient.
2. Publication in a scholarly journal of the carbon-14 tests that show the associated leather to be ancient and of a comparable date to the lead.
Even if the antiquity of the materials is demonstrated, this proves nothing, since ancient materials are sometimes available on which to write fake inscriptions.
3. Publication of the location and details of the supposed discovery and analysis of the site by archaeologists.
4. Analysis of the patina of the script which demonstrates the writing to be ancient. If it is modern and unretouched, this will be obvious. If it has been retouched to seem ancient, this may or may not be detectable (see the controversy over the patina of the James Ossuary and the Jehoash inscription).
5. Full publication of all the texts with good photographs.
6. Analysis of the script by paleographers.
7. If things still look promising at this point, it will become worthwhile for philologists to take an interest and start trying to decipher the texts. So far, epigrapher Andre Lemaire has seen some of them and does not consider them genuine.
Inevitably, people will be now trying their hand at what is readable in the current photographs (if we assume they are from the same corpus). I don't have time to bother with this right now, but I would be interested in hearing what others come up with.
8. Analysis of the decorations by specialists in ancient iconography.
9. Publication of all of the above in peer-review journals and monographs.
There's probably more, but this is what I can think of off the top of my head.
So ... don't hold your breath; this will take some time. I repeat, I am very skeptical, but I would love to be proved wrong.
Additional background here (immediately preceding post).
UPDATE: Press release here.