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).
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?
0.01% of billions is a lot of money.
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.