I'm a firm believer that Blog Comments - those with High PR and low OBL, that is - still offer some real, genuine value when it comes to increasing your SERPs.
I'd suggest you:
a) Remember to use blog comments as one part of a larger, varied link building campaign.
b) Focus on commenting only on blogs that are relevant to your keywords - don't get tempted to chase 'High PR' links that don't have a thing to do with your site.
c) Offer value in your comments and don't just 'hit it and quit it.' Engage the blog author and the other people on the site who are making legitimate comments. If the blog is relevant to your site, like suggested, the people involved in this conversation are literally your target audience - the people you're hoping to drive to your site.
Blog comments still hold immense value, I feel. You just need to be more selective of where you place them and hold yourself to a higher standard when it comes to what you actually put into your comments
