Feature are the management unit for function in Eclipse.
The plug-in developer should not share plug-in without a feature; as a
consumer of plug-ins
you should demand that they be packaged using features. The Update Manager
can only manager
features; you have to work with unmanaged plug-ins by copying directories.

using about.ini file in feature you can customize eclipse

例如：

from The Java Developer’s Guide to ECLIPSE
http://www.ibm.com/developerworks/opensource/library/os-ecfeat/