I got on the waiting list at the very beginning of 2008 and ended up waiting 17 months for my 2.0 production slot to begin. I can confirm TEG's comments that there were more options available in those days. One particular option to look for is colored leather in the headrest;
I've seen older Roadsters in the field with that option, and it reminds me of the results I got while playing with the web site. I had my options selected for over a year, but not locked in, and when my production slot came available I received an email detailing that some of the other options had disappeared.
I was just happy that they had not removed the options that I really wanted. It's fairly normal for car makers to reduce the number of available options because it speeds up the production line. On the other hand, they added two body colors over time, one in 2009 and then Lightning Green was the last color added.
Regarding vfx's comments about owners buying their way in to the front of the line, this was official Tesla Motors policy starting in the 3rd quarter of 2008. When I entered the waiting list in the first week of 2008, all 2008 models had already been "sold" out. I was waiting for a 2009 model (although we now know that there never was a 2009 model, just 2008 and 2010). Around September, Tesla Motors announced that $16K extra would allow someone to cut in line and get a 2008. Basically, 8 months after being told that no 2008 models were available, I learned that other people could buy their way in front of me in line to get a 2008. Considering that the "2009" model was $10K more than the 2008, I think the effective buy-in was $26K total. As you might guess, I complained seriously about this to Tesla Motors. Their response was that 2008 models had become available due to attrition, so they moved up all of the remaining 2008 owners to earlier production slots, offered 2008 models to 2009 "owners" who had expressed an interest previously, and then offered the few remaining 2008 production slots to the public at a higher price. Tesla Motors basically said that they realized that 2008 models were "worth more" than 2009 models because of the "first year model" status of a new make for collectors and such.
In the end, it didn't really matter so much, because I had to give up my production slot thanks to the stock market and general economy at the time. Strangely enough, I fell victim to another timing issue. When I purchased #1244, all "custom order" Roadster slots had been "sold out." So I selected an "on spec" Roadster 2.5 that magically matched my options (except for the crappy Infotainment system). After I took delivery, though, Tesla Motors announced that there were suddenly 100 more "custom order" slots available again. I don't know whether to be happy that I got my Roadster without waiting, or upset that Tesla Motors once again changed the rules after I gave them my money. I suppose I should just choose the happier thought.
As for the "on spec" cars, I was told by a Tesla Motors employee that Roadster sales died down in the winter because nobody wanted to think about a soft top convertible when it was cold outside. This strongly implies that they had more than one year of "on spec" cars, or long enough to notice a seasonal pattern. Then again, I suppose they do not have to completely lose demand and get behind production just to notice a trend.