If you are an android developer and developing android apps for android phones i.e in android 2.2 and wish to run it in all devices then technically there will be no issues but there will be a serious problem when you will see the same app running in an android phone and an android tablet. The user interface will not be as you have designed it. The First thing the developers should remember is for an Android phone the default view is portrait so when we design for it we design according to the portrait view but in an Android tablet the default view is landscape view so whatever we have designed keeping portrait view in mind get stretched and truly said the app looks pretty bad.
So for Android tablet we have to keep it in mind that it has lots of spaces on its 10″ screens so can use the whole screen. so we can divide the whole screen in 2 parts which is called fragments here is some helpful links for all developers