Why not? Unless there are outstanding issues or disputes that can't be easily resolved, there is no reason why you shouldn't still talk. A good relationship is based on several things, one of which is friendship. There's no reason you can't still be friends if the other things have possibly disappeared over time.
Although I do believe the above answer is true - you do have to ask yourself why you feel you need to still talk to your "ex". If you tend to live in the past so to speak how do you expect to move on into a healthy relationship. Unfortunately there are not many spouses that will be happy with you conversing with your ex even on a "hear and there" bases and if you intend to hide something of that nature you definitely are not ready to move on. You should take some time for yourself without your ex and to give yourself a break to find what you really feel and think. Your "ex" is your ex for a reason and that is something to consider.