Of course your map is wrong; you don't live on an Interstate. A few points to make on the digital mapping companies responsible for all the maps, update cycles and TIGER. And some bias, I was a former employee of one of the digital mapping companies.
In the US (And globally) There are two companies that are responsible for all the digital maps Tele Atlas (Owned by TomTom) and Navteq (Owned by Nokia). If you look at any GPS device or online map site you will see a copyright from one or both companies. Their business is driven by getting people from point A to Point B the fastest i.e. by routing you to nearest highway and having you drive on it for the longest amount of time possible. The main focus is the US highway system: Interstates, US Highways, State Highways, Regional, County and Municipal Routes and the major metropolitan areas. If you don't live in the metro areas there is very little business need for correcting the errors in your locality. Why fix the streets in Stowe, VT (pop 6,000) when many more people will be served if the streets and addresses were updated in Cary, NC (pop 130,000 metro area of Raleigh, NC)?
Each company works on a quarterly update cycle where a new version of their mapping database is available for purchase every 90 days or so. Some customers get the quarterly updates some get annual updates. The GPS units and online mapping sites are only as good as the currency of their maps. Make sure you update you maps every time an update comes out. There is always construction and changes in the road system and old maps will not reflect the newer changes. Just because Google Maps says the copyright is 2008 doesn't mean the map has been updated recently. I know when I was working for the mapping company we were working on a huge project for a car company that would be taking the mapping database produced in Fall 06 and using it for the navigation systems in their 2008 cars. If you do have a specific problem go right to the source to get it fixed Navteq map reporter or Tele Atlas Map Insight.
The US Gov't does have a free nationwide map you can use TIGER (Topologically Integrated Geographic Encoding and Referencing) Produced by the Census Bureau. When was the last Census done? 8 years ago? Yea that gives you an idea of how accurate the TIGER map is. TIGER was made for government applications showing very accurate municipal boundaries and topology of streets.
To get an open source Map project going you will need a good sized server, Volunteers in just about every municipality, good database software that can hold every thing you ever wanted to know about streets (name, address, one way, truck and vehicle restrictions, routing info, Points of Interest, zip code, real time traffic data, gated communities, municipal boundaries, state locality, ect...) a great set of possionally accurate aerially imagery (preferable 10m acct or less) for alignment of streets, and did I mention a large army of helpers in every municipality.
Just make sure you get the newest maps updates for your navigation device and go directly to the source for map fixes: Navteq map reporter or Tele Atlas Map Insight.