I am not certain when (or even if) B or A's rooftops will re-open. The A/B facility as you know has been open for some time and according to a fellow IAH spotter who now volunteers to guide tours of IAH on the behalf of HAS, says that C and the A/B rooftops are now open and that spotting and photography are ok for the time being, but you may however be approached by security.
Before 9/11, I would often go up to the roof of B terminal and photograph, although it was shut down for parking, actually it was rather nice not having to dodged cars. It would not suprise me if it were closed off altogether now in light of 9/11.
Say, I have not seen a post from you on the IAH Spotters Club for some time, though I have been rather quiet from that site as well.
"Show me the Braniffs"