How about all the publicity they got from it for free? I'm sure visits to apple.com got a big bump today thanks to that. Apple.com is on the frontpage of every social sites right now (reddit, digg, hn etc).
To do noble and good things while following your business' charter: this is appropriate and an attractive goal for us businesspeople, if you ask me.
Even with added traffic, the conversion rate (visitors/buyers) given the tribute and no products on the front page has to be extremely low. Low enough that I tend to believe they are losing money for the sake of this.
Apple is a company that has billions in cash. Any amount of money lost because of this won't do anything to their bottom line, something like 0.01% maybe less. The amount of free publicity and props they got from that action however are worth millions, I mean, just read what people are saying on this thread, they're all praising apple. How much do you think that's worth as publicity?