Road Map for the Digital City: Achieving New York City's Digital Future is very well presented and an interesting read.
The tenets of Open Government in the doc are:
1. Open Government democratizes the exchange of information and public services, inviting all citizens to participate and engage.
2. Open Government connects citizens to one another, supporting more efficient collaborative production of services over the traditional mode of citizen consumption of government-produced services.
3. Open Government information is more valuable when it is collected at the source, and published in near-real-time.
4. Open Government data is machine-processable.
5. Open Government invites all information consumers- inside and outside government - to correct, improve, and augment data.
6. Open Government uses open standards, formats, APIs, licenses, and taxonomies.
7. Open Government is accountable and transparent, perpetually self-evaluating, iterating, and exploring new ways to solve old problems.
8. Open Government makes as much information as possible available to as many actors as possible and is designed to minimize financial and technological barriers to accessibility.
9. Open Government enables efficiency, cost savings, and the streamlining of government services.
10. Open Government is compatible, nimble, and mashable, fostering collaboration, coordination, and innovation with other governments, academic institutions, and organizations.
I like the "compatible, nimble and mashable" characterization. That sums it up really.