I've seen a couple of times similar behavior where a site disappeared from google's results for a couple of days, after some content and theme changes but everything was back to normal after that. In any case καλή τύχη.
I made the change on the 16th, so it's been nearly two weeks now... Hopefully it will return, it was very nice to be able to say "I'm ranked just after python.org for 'learn python'" :/
Thanks for your help!
Perhaps Google has reevaluated your ranking for these keywords, as there are a lot of PR6-7 sites but yours is a PR4 (at least according to the SEO Site Tools extension).
Your best bet is to follow infinity's advice and start blogging more frequently, while targeting specific keywords for your posts.
You mentioned that you've set up redirects from the old site to the new one, are you sure that your content doesn't appear twice, using different url's? (ks.net/node/1 and ks.net/tutorials/First) This will be penalized by Google.
Also your /tutorials url redirects back to the main domain, is this by accident?
/tutorials/ points to / because I removed the page that was there and linked to them in the sidebar. I have no idea why Google would take the site from 6 PR to 0, wow...
The reason your site dipped out of the rankings is because when Google crawls a site and there have been significant changes to the structure (new theme, new internal linking structure, missing pages, etc), they yank you out of the index in order to reevaluate your proper position before moving forward. This can take a day, a week, a month, or half a year to recover; there is no way to predict how long it will take.
Try and replicate as much of your old site's structure as soon as possible, and just give it time.
Thanks again!