Is it absolutely necessary to have tent reservations? I thought that since we couldn't make our hotel reservations until January (2007) that the tents worked the same way, aparently I was wrong. How easy are the tables to come by that are open to people without reservations??

You'll probably need reservations to get in after 7pm. We normally get our resrvations a year in advance.
However, you can try to sneak in...
The outside decks don't need reservations.
It's a WILD adventure...but fun...

It depends, when you plan to go. On Weekends, especially on Saturdays, tents are closed quite early due to overcrowding (and normally, they don´t open again the same day). I´ve been there last year, on Sunday at the second Week-end. We've been at the tent at 10am and the tent (and all other tents) were closed already. 2 hours later, they even closed the Beergarden areas around the tents. We then proceeded to the Beergarden in the Englischer Garten. I don´t know, from what point of time reservation is possible, but if you plan to go on a week-end, I'd strongly recommend to do a reservation. During the week, there is much more space, you'll probably be doing fine then without a reservation. Discussion with the security staff is absolutely useless. Reservations are moreover not unlimited in time, but restricted to something like 2 hours. After that, you have to clear the table to the next guests. Also, the reserved seats are often not in the heart of the tents, but on the fringes. My advice (so did we the year before ): Do a reservation, stay at your table until about 30min before you actually have to leave and disappear into the anonymous masses of the tent. But note: You will not be served a beer, unless you are sitting at a table, so squeeze in just to order, then you may get up again (with your beer). Along with your reservation, you have to pay a minimum consumption of something like 20€.

This is the tent we went to.: http://www.oktoberfest.de/en/03/content/braeurosl/
We went on a Tuesday at about noon and stayed until 9 with no reservations. They have tables that don't require reservations.
http://www.thirdmansystems.com/vacat...s/DSC01952.htm
This is a picture of the tables where we sat at: http://www.thirdmansystems.com/vacat...s/DSC01975.htm
On opening weekend you better be there as soon as the tent opens. Please see the parade. Some folks will reserve a table and then sell the extra seats.

We were at Oktoberfest last year (2006) for the first time since the early 90’s. In the early 80’s we lived in Munich. In August, I would have to go down to the Brewery in person to reserve a table. I would have to pay for 2 beers and a half chicken for 10 people, one table. This would reserve a specific table for the evening starting at about 6 pm. After about 8 pm if you got up the table became free for all. Things may have changed.

In 2006, without reservations we went for Sunday and Monday of the second week. I would say it depends on when you go. On Sunday there was little problem finding a place to two. The bigger your group the harder it will be. On Monday, we had to have a beer and dinner outside in the beer garden, but after dinner, we wandered the tents and found a place about 8 pm. Just wander the tents and wherever you sit, that’s it, don’t move.

For the serious beer drinkers there is Stark Beer Fest (Dark Beer) in March (9-25 in 2006). We hope to get there for a day or two this year as well

I believe the reservations must be made for a minimum of 10 people.

Yes, generally you have to book a whole table. However, to cater to the many tourists who come here, you can book accommodation and reserve your seat in a tent through the Munich tourist office website at this link -http://www.oktoberfest-munich.com/?adv=muenchen.de. As someone mentioned above, you pay for a seat, food and drinks at a set price. The price varies according to the tent but is around the €30-35 figure. The offer above gives you entry to a specific tent, I think. You will get vouchers entitling you to two 1-litre mugs of beer (or substitute) and the rest to be used on food. If you don't use up the vouchers, you can try to sell it to other people in the tent or forfeit it. Of course, you can order more food & drinks a la carte.