Oh, never mind. I found it.
Under Settings > General > Accessibility there is a new option: Speak Selection.
Once turned on selecting things in iBooks gets fairly unpredictable as to what menu pops up. If you select more than one word, you suddenly get Speak as the only option. After that even selecting one word seems to get the Speak option; though sometimes waiting bit, or turning the page seems to reset this behavior.
If you highlight text first, then the menu that pops up has more options and an arrow to the right. The arrow leads to a menu with Speak.
So at this point, the method of getting the normal menu back in iBooks appears to be to go into Accessibility and turn the Speak Selection option.
Hmm, you can also have it highlight words as it speaks them. Cool, I guess.
P.S. I'm guessing this is a bug in iBooks, since the Notes app appears to act more constantly, menu wise.