Are you looking for an Automatic Save feature or an Automatic Backup, which are two different beasts?
There is no Auto Save feature in CS5, as another poster already informed you.
But, if you want your files automatically backed up every day (all the files and folders you choose, not just Illustrator files) you can use Mac's Time Machine in OSX, or you can purchase a program such as Retrospect that will do it (available for both platforms).
On the Mac side, I prefer Carbon Copy Cloner for this. It's Shareware and works great. You'll need an external hard drive to hook up to.
Well then I think Mr. Macy should know that either the program needs to to be updated so that it doesn't crash twice a day (different files, different Macbook Pros with same hardware and same Mac OS X systems) while doing simple things like copying and pasting text or changing an objects color. We lose hours a day recreating work lost during crashes. Saving periodically is a great idea in theory but most other products, including other Adobe products have an autosave option, knowing that people don't always save every five minutes on the dot, nor do programs never crash. Ironically, the great software that does have autoback (such as Autodesk 3D Studio Max and Maya for instance) don't even really need it and I only use it when I screw something up not when from software crashes.
I'm noticing that instead of fixing simple bugs in Illustrator, more time is spent making it work with the whole suite and adding rediculously superfluous new 'features'. If someone wants a list of known and reproducable bugs let me know and I will post them. And yes, I have reported the bugs through the crash reporter many times with no response and no fixes and worse no response to posts on this forum.
Why are you always defending the ridiculous aspects of an entity that needs no defense and to which we have no recourse?
And, I wasn't wating around. Unlike you. I was googling for auto-save in Illustrator in the vain hope that it had something as sensible as this... and this was the first result from and Adobe domain, but nowhere near the first result.
So go back to lurking the threads and chasing down my posts. Stalk me all you like. I'm not afraid
You should not be afraid, you should read the manual. And you are not so important that I would stalk you in anyway. But you are wailing around in several forums here since 2 days with more than 80 posts in that time frame exactly in those forums where I am trying to help other users and where I am qualified as an ACE and ACI since the earliest versions up to the latest possible one. So it is unavoidable to meet you there several times and become upset because of your wailing.