I am very ashamed to say this, but what about outlook calendar integration? In many big companies rooms are still booked that way... also, maybe you want to make your page customizable so that you can put the company's logo. Finally, login: if I am using a company's laptop, I don't want to remember a password for each service I use.
No shame there at all: I dislike Outlook, but calendar and resource manage in Exchange is pretty frikkin' awesome. Microsoft got that right a long time ago, no one comes close yet. AFAIK. YMMV. IANAL, but that's not really relevant.
What exactly is the difference between this one and the one you posted a few hours ago?