The best thing to do is look at your requirements and make your purchasing decision based upon that. As Kboland mentioned, there is always something new just over the horizon so waiting for the next best thing is a hopeless cause.

On ICS, I get the impression that most Android devices are based upon Gingerbread. This means that app developers are going to target Gingerbread for some time to come. So you will can still move forward with current devices. I also doubt that the iOS ecosystem is going to have much of an impact on the cost of Android devices at this point. Performance and features, sure. But Apple's prices are in a league of their own, which means that a lot of consumers will barely give Apple tablets a cursory glance before choosing the competition.