Number of IoT Platform providers are increasing as we speak. Here are the list of top 49 providers with some great offerings. While there are subtle differences in what they offer , most of the targeted use cases are overlapping and they have a common objective. The objective is to have a cloud hosted, horizontally scalable and device agnostic platform to support messages from low foot print devices hooked up to high latency (more delay), low bandwidth (smaller pipes) and possibly un-reliable networks.
I would like to call this as IoT-as-a-Service (IoT-aaS).