I started in July 2008.

I did it primarily for health reasons, especially with regard to chronic diseases, and the data for that obviously isn't in yet.  However, I did manage to get rid of some nagging problems, including chronic painful gas and hemorrhoids, and also stopped the progression of farsightedness and skin wrinkles.  I wasn't trying to lose weight, but I did lose some fat, going down from 155 lb to 138 lb (5'11").

Rather than cutting and pasting and getting incomplete lists when people post at the same time, could you edit your original post to maintain the list of dates?

I started May 2006. As for achieved?  How would you define achievement?  My main goal was to be able to get through a long day which started when I woke up at 4:00 am and lasted until I got home at 7:15 pm.  A high carb grain based diet had me eating 5 to 6 small meal during the day, but I still had great energy dips in the afternoon. Also eating that many small carb based meals ruined my teeth and I am still dealing with that today.

For me now it's one year.
I have tried loooots of diets but nothing really worked for me, the nutritionist either. I heard of the paleo and got the book last year. I decided to try it for a month, just a month, I thought all that protein was going to cause damage, and I was a vegetarian (ROFLMAO!!!). Anyways...for just a month...it worked, and it was a great month. But I had it in my mind it'd be just one month so I stoppd after that. And put everything back on. In February 2009 I took the decision of doing the only thing I knew had ever worked for me. PALEO!! And this time, I meant to do it forever. So now it's been one year, I must say the decision I took 50 pounds ago was the right one.

august 2009, I was actually skinnier before paleo then after. I tried it because I read a lot of info about carbs and how they aren't essential for life and the fact that the food pyramid said to eat lots of carbs led me to believe something is very wrong

Since Sept 27th, 2009. Started at 160lbs (@ 5'6"), went down to 133lbs and am now ~ 137lbs since lifting weights regularly.

My wife and I started eating paleo at the end of 2005.

I did it for overall health reasons (I wasn't very fat or anything).
I lost the belly that I did have and now I'm focused on building some muscle, which seems to be going well.
I no longer have join pain (I used to have a horrible knee) * caused by nightshades
I am sleeping much better (I had something like delayed sleep-phase syndrome)

My wife has lost about 15kg and she is very close to her ideal weight.
She had:
Bad asthma (daily Ventolin use and hospital once a year) - now almost completely gone (she uses her inhaler maybe once every 3 months) *caused by dairy
Frequent migraines - now completely gone * caused by grains
Constant yeast infections - now completely gone * caused by sugar
Reoccurring tonsillitis (she can't get her tonsils out being an asthmatic) - non since being paleo

Started july 2009. Main reason for starting was acne. I had really horrible case of acne, I am talking about more than 20 cysts on the face at once, and about 10 on each shoulder. I was 19 when I started (20 now). I have experimented with different paleo renditions and what I have noticed is that it just takes time to completely heal. 3 months into the diet and my shoulder acne had completely disappeared. Facial acne persisted but was much better. At the beginning of this year my acne was well enough that I stopped all topical medication (had been using topical medications for years, the 20 cysts at once was when I was using medication; yes, that bad). Shortly after stopping topical medication I also dropped fruits from paleo and have been experimenting with that since then. It helps heal acne faster, but after my acne is completely gone I am bring fruits back and I am sure it is not going to be an issue acne-wise (I just dropped fruits to speed up the process).

Today my acne is even better. Shoulders have been clear for months. On the face I stopped getting so many cysts, now I get around 2-3 smaller cysts at once and some white heads. That is without using topical medications. Other unintended side effects: improved racquetball performance (although dropping the fruits has really hurt it, that's why I will reintroduce them once I am clear), feel awesome, visible abs, and many other.