Reader CrazyRower sends word of something small, but cool coming to iChat in Leopard. According to screenshots from an account named after Apple's favorite designer, sending a message to an SMS number is now builtin to the iChat File menu.
As we've reported before, this is hardly a new feature-- you can do it with your iChat (or any other AIM enabled program; I did it on Adium) right now. All you have to do is go up to File, then New Chat, and instead of the AIM account name, just type "+1" and then any SMS enabled number. And whoever you message can even reply from the phone, and their reply will appear right back in your chat window.
But it is cool that it will be built right in to iChat's menu. You'll be able to send driving directions to your non-iPhone (or just bother your girlfriend with text messages while chatting online at work) that much easier.