Recommended Android Software to learn Mandarin

I personally use these everyday as I'm learning Mandarin/Chinese on my Motorola Droid.

Search for these on Android Market:

Google Pinyin

This is an IME, so once installed you need to enable it in Language & keyboard. Long press a text field to select it. Use ctrl-space to switch between Chinese and English, which makes the Android default keyboard unnecessary (except if you need to input a third language...).

Very smooth, easy pinyin input with good suggestions and clear, readable fonts.

Google Translate

Although complex sentences translation is generally poor, the interface is quick and fun to use with a tons of little features (such as copy to clipboard on tap, voice recognition, suggested translations, romanization, pronunciation, etc)

Hanping Ch-En

Great to look up individual words and star them offline (example: if you're travelling to Taiwan or China...). Much more reliable definitions than Google Translate since it is based on the well-known CE-DICT dictionary. Buy the Pro version, worth the (small) price of admission.

MortPlayer

Great to play audio books (such as the Pimsleur audio books). It also helps keeping your audio books apart from your music player.