Talked to jeremy on irc a bit tonight and this bug got brought up:

<halfline> that could actually cause other problems                  
<halfline> right now we do                                           
<halfline> plymouth --ask-for-password > password.txt                
<halfline> and then cryptsetup luksOpen --keyfile password.txt       
<halfline> if plymouth isn't running then password.txt is going to be empty
<jeremy> and we do it whether or not plymouth is even installed      
<jeremy> that's 453678                                               
<halfline> well, pjones made a nash internal called plymouth         
<halfline> s/internal/built-in                                       
<jeremy> yeah, but it's a null command.  so it doesn't actually do anything
<halfline> i fixed the password interface today though               
<halfline> so now you can do plymouth ask-for-password --command="cryptsetup
luksOpen --keyfile -"
<halfline> and it will call the command for you in a loop until it returns 0
exit status
<halfline> so we need to update mkinitrd to make use of that         

So we need to change mkinitrd to use the new interface and either 1) make
plymouth always run or 2) make the plymouth null command less null and run the
--command part

We're working around this for F10Alpha by making mkinitrd require plymouth. This
ensures that plymouth is always installed.

And that's the approach we're going with in general.  plymouth is just a part of the standard boot sequence