Woke up to a lovely morning tweet: "@lizcastro Done. Update available now in App Store that supports library books." from @micahsb, a developer and entrepreneur. He was referring to the fact that the new version of their Bluefire Reader app for the iPad can display Adobe DRM'd EPUB format ebooks that you've taken out of the library.
And it works! I connected to my library, and quickly did a search for Adobe ePUB, “took out” and then downloaded The Mysterious Benedict Society, which we're in the process of reading, and clicked OK when I was asked if I wanted to open the file in Adobe Digital Editions. This converts the download file into a Bluefire-compatible Adobe DRM'd EPUB file and places it in the Digital Editions folder, within the Documents folder (or My Documents folder on a PC).
Next, I opened iTunes, connected and selected my iPad, chose the App panel, selected Bluefire at the bottom of the window in the File Sharing section, clicked Add..., chose the book file from where it was copied—in the Digital Editions folder within the (My) Documents folder—, and then clicked Sync.
I then opened Bluefire Reader on my iPad, and there was my book! Absolutely lovely.