Part 2 of the sous vide primer series is up on Cooking Issues. This entry focuses on low temperature cooking without using a vacuum/cryovac machine. There's some great info, including a genius technique for getting most of the air out of a Ziploc bag using a large container of water to squeeze the air out around the food (see the picture below).
Dave Arnold also explains the current rules for sous vide cooking in NYC, which make it incredibly difficult vacuum seal food...
When I first moved to the city, the restaurant I trailed at would vacuum seal food products, then wrap the sealed food in 5-7 layers of plastic wrap, then wrap that in 3-4 layers of aluminum foil. I asked why and was told that the food inspectors somehow never took the time to unwrap all the layers around the vacuum bag, which happened to be outlawed at the time.
The next week I took a job at a different restaurant and went to bag & seal up a sheet tray of quail. When I finally found the cryovac machine, there was a huge note plastered on the side that said "DO NOT USE!!!!!!!!!!!!!!"
The machine worked fine, the note was just there in case the health department stopped by before we had our final HACCP plan in place (the HACCP plan is how sous vide cooking in NYC has been reconciled, and it takes a whole lot of work to maintain).
Be sure to check out the full article
for all the information; it's a fascinating read.