Can I use a PC3-10600 memory on a MacBook with PC3-8500 slots? I have a MacBook (13-inch, Late 2009) with the default 2GB of RAM, I want to update it to 8GBs, but I only found this model of memory to buy.

The question is since the memory is more "powerful" than the slot it will work? Will I have any issues? If not, what should I buy? only PC3-10600?
You should be able to use the faster RAM without a problem.  No guarantees when it comes to RAM compatibility that hasn't been vendor qualified (which is seldom an option) so make sure you buy from someone with a good return policy.

You might consider buying through somebody like OWC (macsales.com) that specializes in Mac parts.