They left out some specific cases dealing with police.
Johnson vs. Sequim: http://law.justia.com/cases/federal/...88/676/569794/
State vs Flora: http://www.impsec.org/~jhardin/gunst...e_v_Flora.html
It's the consensus that when public officials are engaging you in their "public" duty you can record without them being aware of the recording. Especially when it is in a public place.
Another case that support this line of thinking and how our state views it.
State vs. Clark http://www.impsec.org/~jhardin/gunst...e_v_Clark.html