Replying to my own question. (Score 3, Interesting)

Perplexed as to why Amazon would launch two separate Question and Answer services, NowNow and AskVille I did some googling and thought I'd share what I came up with.

Firstly, it turns out that someone has already asked this on AskVille and the answers are fairly to the point. Also O'Reilly Radar has a post about the two services.

The gist of it is: AskVille is like Yahoo! Answers and NowNow is like 82ASK. NowNow is specifically set up for mobile users who need to find answers quickly. Questions are farmed out to Mechanical Turk where people are paid real cash money to answer questions.

However, Amazon have completely dropped the ball with NowNow:

1. The interface is mobile email! It's specifically for mobile phones and yet they've used email instead of the obvious choice of SMS.
2. Because they've chosen email instead of SMS they've also made the billing procedure more complicated. While the service is beta it is free, but I presume that in order to use it when it goes live you will have to set up some sort of Amazon account. So you have to know in advance that you might one day need to use the service, unlike with 82ASK.
3. Mechanical Turk is notoriously badly paid, and absolutely anyone can join it. So the researchers aren't vetted or trained like 82ASK's texperts are, and they're nowhere near as well paid as texperts, so they can't guarantee the same quality of answers as 82ASK.

AskVille has some interesting twists on Yahoo! Answers. Like an online game answers earn virtual money, and there is more community vetting and rating of answers and answerers then there is on Yahoo! Answers.

If they'd been really innovative they would have merged the best bits of each into on single product with both mobile and web access. If they'd done that there would be reason for 82ASK to be worried. But as it is I think they've blown it.