Q: ibooks author for Mac os 10.6.8 is there an ibooks version for this system?

Sorry, no. 10.7.4 or later is required.

Upgrading from Snow Leopard to Lion or Mavericks

To upgrade to Mavericks you must have Snow Leopard 10.6.8, Lion, or Mountain Lion installed. Purchase and download Mavericks (Free) from the App Store. Sign in using your Apple ID. The file is quite large, over 5 GBs, so allow some time to download. It would be preferable to use Ethernet because it is nearly four times faster than wireless.

     OS X Mavericks- System Requirements

       Macs that can be upgraded to OS X Mavericks

         1. iMac (Mid 2007 or newer) — Model Identifier 7,1 or later

         2. MacBook (Late 2008 Aluminum, or Early 2009 or newer) —

             Model Identifier 5,1 or later

         3. MacBook Pro (Mid/Late 2007 or newer) — Model Identifier 3,1 or later

         4. MacBook Air (Late 2008 or newer) — Model Identifier 2,1 or later

         5. Mac mini (Early 2009 or newer) — Model Identifier 3,1 or later

         6. Mac Pro (Early 2008 or newer) — Model Identifier 3,1 or later

         7. Xserve (Early 2009) — Model Identifier 3,1 or later

To find the model identifier open System Profiler in the Utilities folder. It's displayed in the panel on the right.

Are my applications compatible?

         See App Compatibility Table — RoaringApps.

Upgrading to Lion

If your computer does not meet the requirements to install Mavericks, it may still meet the requirements to install Lion.

You can purchase Lion at the Online Apple Store. The cost is $19.99 (as it was before) plus tax.  It's a download. You will get an email containing a redemption code that you then use at the Mac App Store to download Lion. Save a copy of that installer to your Downloads folder because the installer deletes itself at the end of the installation.

     Lion System Requirements

       1. Mac computer with an Intel Core 2 Duo, Core i3, Core i5, Core i7,

           or Xeon processor

       2. 2GB of memory

       3. OS X v10.6.6 or later (v10.6.8 recommended)

       4. 7GB of available space

       5. Some features require an Apple ID; terms apply.

You don't need iBA to produce ebooks. If you must stay with your 5 year old OS, you could use various other apps to produce .epub format.  This has the advantage that it can be read on all platforms, not just the iPad and OS X 10.9.

Depending on the type of book you have in mind... there are a number of  apps which create ePubs on the iPad.

Obvioulsy not as comprehensive as iBooks Author. I have tried a few and stick with Book Creator - which has a free trial. I think I paid about $3.99 for it and its end products can be  found in numbers on the iBooks store.

I am not sure  how you would  upload to the  iBooks store -  if your OS will not support iTunesConnect and iTunesProducer.