Great news. The new version 2.8.5:
The conversion of an epub to plaintext is quick and useful.
I do not see any use for the search if I cannot display/read the epub!
I am not aware of any Quicklook plugin that lets me read the epub. There are some plugins that let you see the cover and read metadata (a brief description).
But… Thanks!
Third party free app called Calibre lets you convert ePub and numerous other file formats into a desired one.
Yes. But I would like to be able to read epubs inside DTP!
Stay tuned 
It sounds good to me!
Thanks
I have the same questions…
(1) I index an existing books from iBooks. All I see in DTP is the book’s cryptic file name (see d.pr/i/TxO0+). It appears that I can, in fact, search into the book, but I cannot see any of the books’s contents.
(2) I installed Calibre as you suggested above. Whenever I try to load an iBooks-format epub book into it, it says it cannot understand the book’s format.
Am I missing something? It doesn’t seem as if the epub indexing feature is much of a feature. 
Aren’t books from the iBooks store DRM’d?
Yes, they are - and as such, they are not readable in other epub readers.
I have used Calibre in the past and converted my ebooks to PDF so I am not tied into any specific ebook reader. Works fine for me with purchases from Kindle, iBooks and GoogleBooks. I then have the flexibility to import them into DTPO, read, highlight, etc to suit my requirements. One thing to note when doing this is the page size/layout needs to be set correctly to maintain similar formatting to the original device as shown here:
Any updates? 
The quicklook generator at github.com/GenjiApp/EPUBQLGenerator seems to do the job well if set to show the whole document.
Is it possible to import, OCR and search ePubs in DT3? And also read them/display the text.
There should be no need to OCR EPUB files.
See Help > Documentation > Documents > Office Documents, Email, and Others > EPUB.
Yay! I can now search and read ePub in DT. Me like;)