I did mean blogs running Wordpress and hosted on another server although wordpress.com blogs can also climb the ranks easy enough too. I have one wordpress.com blog that hits #1 for all sorts of keywords over taking the authority sites in that topic. I dont build on backlinks, use keyword rich post titles and actually only post once a month to the blog. The blog has a PR4, gains backlinks by itself and gets 100 daily or so readers which isnt bad for a blog that has had very little work done to it.
Did your Wordpress blog not suffer from the "PR strip" imposed on Wordpress.com a couple of months ago? Mine lost all PR and still stays on PR0
I guess you are just 1 of the lucky bloggers who makes a successful launch. By building backlinks automatically it means that you have a bery good site that interests readers which then spread through word of mouth.
How much traffic? Im guessing not a whole lot but I could be wrong. Do keep in mind that after the sandbox your rankings will crater.
As far as I seen it didnt but it did happen with one that I host myself but all the PR came back on the last update.
Also if it is the google bonus for a new site, it's a success... i think that use wordpress will be a must in a few months.