For the last 18 months Google has allowed you to upload your own PDFs and EPUB files to your personal Google Books account. Unfortunately, you could only access those uploaded files through a web browser or on the Google Books Android app. That has changed with the latest update to Google Play Books for iPad. The latest update to Google Play Books for iPad enables you to read your uploaded files through the app.
Other updates to the app include the option to categorize and sort books, double-tap to zoom, and a new material design to match that of other Google products like Google Drive.
Uploading PDFs and EPUBs to your Google Play account could be a good way to get things like public domain works found on Project Gutenberg from your desktop to your iPad.
H/T to The Next Web.