I've posted quite a few comments over the weeks to blogs I know for sure are 'dofollow', and yet, none are showing as backlinks in google. Anyone have an idea how long they take to show up? On the other hand, I guess if google doesn't know a blog has had a comment left, then it won't know to index it - so has anyone ever taken to using pingomatic to ping blogs you've left comments on?
It takes a while before Google updates the backlinks of your site. Usually, you wouldn't see any changes in the number of your backlinks until Google makes a PR update so pinging blogs you've left comments on doesn't really help. Be patient, as long as the blog is a dofollow blog, I'm sure Google will count in as a backlink for your site during the next PR update. Just continue building your links and if you're buying links, make sure it's going to be 3 to 6 months duration because that's how long before Google updates backlinks and PR.
Google the exact url and see what date they cached it. Like Jackieshine said.. Patience is needed if it hasn't been cached since you posted. Holla!! Ronripple baby!
I seldom find backlinks until a few weeks later in Google. But I generally find the backlinks in my awstats within days or possibly a week or 10 days from the posting in the blog.