Google docs is certainly helpful for people who cannot afford or are not interested in having their own software appications like Word or Excel. Though the functionality is less it is still sufficient for people who are only interested in creating simple documents.
A small library with limited resources and strong community network may find Google docs and similar programmes useful. Without the necessity for expensive software, that is probalby more sophisticated than needed, they can create and use simple spreadsheets, wordprocessing doucment etc, that can be shared around with ease.
As with all network applications it can allow a library, particularly those that operate in small communities, to engage more with the community.