Forum Moderators: open
I actually think that there is a critical mass in the number of posts ... around 100 or so.
To get noticed by other bloggers, start quoting THEM in your blog and remember to give them a trackback. They will notice the trackback and follow it back to yours. You could also email them to let them know that you qoted their material.
If your blog isn't likely to be an object of admiration to fellow bloggers then get an entry added to blog directories - but beware, the people assessing your blog for inclusion are pretty savvy and know the difference between a real blog and an attempt to earn advertising dollars.