So far, the best (unofficial) place I’ve found to get a complete list of ballot measures is at Ballotpedia. If you type the word <Oregon> into the Ballotpedia search box you’ll likely be linked to this page.
Official sources (and my previous ballot measures post here):
2) Changes and updates will be posted here.
3) Detailed 2008 General Election Measures info here.
Local Measures: For those in other counties with (oh boy) additional local measures, check with your county election office.
Other sources of ballot measure information:
Project Vote Smart also has some information and additional links and don’t forget that Oregon newspapers, the Oregon State Bar (OSB) publications, the League of Women Voters, City Club of Portland, and other print and online resources will all publish commentary on the November 2008 election measures.