It’s taking a while, but Android 4.0, a.k.a. “Ice Cream Sandwich,” is slowly making its way onto more and more smart phones and tablets. According to stats that Google released yesterday, the Android 4.0 operating system is now on 4.9% of Android-based phones and tablets.

The Android 4.0 mobile operating system was launched with great fanfare in a ceremony in Hong Kong last October. Along with the Android launch, a new phone, the Samsung Galaxy Nexus, running Android 4.0, was introduced. The Galaxy Nexus was launched into the US market in December.

Since the October launch of the new OS, device manufacturers have been scrambling to engineer updates for existing mobile devices and preparing new Android 4.0 devices for their release dates. But apparently, these things take some time.

By a wide margin, Android 2.3 (Gingerbread) is the most currently used Android OS. It is still used on 64.4% of Android-based devices.

According to Android.com, the reminder of the field breaks down as Android 1.5, 0.3%; Android 1.6, 0.7%; Android 2.1, 5.5%; Android 2.2, 20.9%; Android 3.0, 0.1%; Android 3.1, 1.0%; Android 3.2, 2.2%.

While a growing number of existing mobile devices are being updated to Android 4.0, and many new devices are coming out with Android 4.0 installed, there are still devices that are being launched with Android 2.3 as their operating system. An example is the T-Mobile Prism, which is set to launch later this week.