Well, I think in today's reality, the policies on the books will stay. But I would think carefully before I used them. I do think face time will count in this economy. You can still bill an 8 hour day from home if the work is there, but if the chopping block comes, they may think about who is a key player, and if they don't see you that often, that may hurt you. That said, what is key?
Key is being known as essential (or close to essential) to the team. Maybe you cover a million different sub-areas such that if they let Johnny go, they know you could pick up slack. Maybe you have developed a great relationship with important client X, who would miss you if they heard you got canned. Maybe there is a hot new area - whatever that is - and you are becoming well-versed in it. These things can help you. Many of them do require face time in the office (yes I realize you can talk to clients from home, I do it all the time).
The bottom line is that you want to appear committed to your job, the firm, and your career. If you want a reduced schedule, I say go for it, but go over and above to be responsive. Don't ever let them have an opportunity to say you were not responsive. Your response may be to ask if something is immediate -- it isn't always. But at least you appear on the ball. Don't give them ammunition. Be a professional. Be on the ball.
Tough times will cause firms to - if not formally pull back these benefits -- then not really encourage their use. Be true to yourself but recognize that there are risks in not always being around, especially at the junior level.