The City of Austin used the Austin Tomorrow Comprehensive Plan from 1979 to 2007 to establish a planning process which governed the growth of the city. It covers transportation, land zoning and economic growth and is available in it's original form in local libraries.
http://www.ci.austin.tx.us/zoning/com_plan.htm has links to a web version of the plan.
The City has worked on an interim update, and the changes are outlined here: ftp://coageoid01.ci.austin.tx.us/GIS-Data/planning/CPC/pcdra
If you check out page 17 of the PDF you can see a good historical chart of the plans to date.
Let me know if you need data on a specific area,