Now Android 4.0, AKA Ice Cream Sandwich, has a specific API for stylus support:
Stylus input, button support, hover events
Android 4.0 includes full support for stylus input events, including tilt and distance axes, pressure, and related motion event properties. To help applications distinguish motion events from different sources, the platform adds distinct tool types for stylus, finger, mouse, and eraser. For improved input from multi-button pointing devices, the platform now provides distinct primary, secondary, and tertiary buttons, as well as back and forward buttons. Hover-enter and hover-exit events are also added, for improved navigation and accessibility. Developers can build on these new input features to add powerful interactions to their apps, such as precise drawing and gesturing, handwriting and shape recognition, improved mouse input, and others.
From this description we see that Android 4.0 will natively support stylus input, including pressure sensitivity and hover capability (depending on hardware support, of course). Developers can use this API to make richer, enhanced interaction features when a stylus is used. This doesn’t seem to include OS-level handwriting recognition, but it’s possible that with this stylus support API, developers may have an easier time implementing their own handwriting recognition algorithms for Ice Cream Sandwich.
Right now, limited functionality is available when using a capacitive stylus on an Android device. Basically it acts as a substitute for your finger, which is pretty inaccurate compared to using a stylus on an active digitizer. With Ice Cream Sandwich, developers won’t have to rely on manufacturers creating their own APIs (as Samsung plans to do with theirdevice) for expanded stylus features.
It’s likely not going to be as great as active digitizers and the specific styli needed for them, but this is probably as close to active digitizer functionality we’ll get, which I am personally very excited to see.