I have an encrypted root, so rhgb asks for the password at startup. Since the kernel upgrade mentioned above, the keyboard stops accepting input 1-2 seconds after the password prompt appears, and I can't type more than at most 1-2 characters of my password. If I disable rhgb, I can see that the password prompt appears and then a moment later, a bunch of logs for loading of USB modules related to keyboard/mouse devices appears. In that case though, the console allows me to type my password. I suspect it might be a problem with the keyboard modules changing the keyboard to a new device, or switching it to a new mode. The text console copes with it ok and lets me type my password, but rhgb doesn't.
This seems to have disappeared again with one of the kernels between 2.6.29-0.215.rc7 and the 2.6.29-0.258.2.3.rc8.git2.fc11.i686.PAE that I have now - I can type my password into the RHGB prompt fine again.