Google Ice Cream Sandwich (ICS) OS, the upcoming mobile Android operating system, will be compatible with both handsets and tablets, according to a post in Android Developers.

A wider compatibility means that any ICS applications can be run either on a smartphone or on an Android tablet, regardless of the screen sizes of the devices.

This obviously will be a step of vital importance for the company to make its next version of Android increasingly popular. Actually, Google has been devoted to unifying the Android smartphone platform and tablet platform.

The current version of Android OS is codenamed Honeycomb. There are endless Honeycomb apps in the app stores online. However, they can only be run on tablets since the Honeycomb is designed to be tablets-only.

With the coming of ICS, Android developers can now be sure that their apps work on both large and small screens.

“Some Honeycomb apps assume that they’ll run only on a large screen, and have baked that into their designs. This assumption is currently true, but will become false with the arrival of ICS, because Android apps are forward-compatible — an app developed for Honeycomb is compatible with a device running ICS, which could be a tablet, a phone, or something else,” Scott Main, a lead tech writer for developer.android.com described in the post.

Keeping this difficulty in mind, Google has been assisting third-party application developers to adapt to the transition from Android Honeycomb to ICS. Main wrote in the post that in order to easily adapt to different screen sizes the developers could use fragmented layouts.

Since Google has not released a software development kit (SDK) for ICS, the developers cannot publish ICS apps yet. Still this advice can be helpful for the Honeycomb developers to be prepared.

This move of Google is a helpful evidence to support the ongoing speculation that the ICS may surface in the short future, maybe in October or November 2011, although the company has not revealed the exact release date.