Working online; Guru, IFreelance, Elance, BitWine...
My thoughts are:
With a bent towards code slinger service providers...
In my travels I have been passively collecting a list of resources to be used in this manner and was optimistic that starting small on one or two of these and collecting strong rating / feedback would be a good approach.
My caution personally and from advisors has always been the economy of scale and whether I could expect to win many bids if they came down to pricing vs. offshore consulting houses or individuals.
The key then is to either compete primarily on capability / niche (very current or very dated but still sometimes required) skill sets vs. price - at least until a strong record has been established. Another alternative is to do business development outside of these sites (or between them) and farm out the bulk of the crank turning to an offshore consulting firm using these sites if your skills lean towards client facing technical / project management. Just build in buffers to the project plan to account for the extra handoffs, communications and possible rework required. Know yourself though, if you're an overly perfectionistic OCD plagued code artist you might not be successful representing other people's work at your accustomed level of quality / elegance (I could also recommend a good therapist).
In practice I have not yet had (made) the opportunity to diligently pursue this plan as I've since decided to refocus on being an employee - will I ever learn??? When I was focused on self-employment business development I found that knowing people was much more important to finding and winning bids than knowing things or pricing level. That would argue strongly in favour of the argument in your blog posting.
One tool to use in building a validated portfolio of work that can be referrenced from any of these sites in your profile is claimID.com (mine is http://claimid.com/mikebd).
Sites I've bookmarked - YMMV:
https://www.odesk.com/
http://www.rentacoder.com
http://getafreelancer.com
http://www.sologig.com/
http://freelancepool.com
http://www.freelance.com
http://www.guru.com
http://drupal.org/node/57624
http://www.php-freelancers.com/
http://www.hotgigs.com
http://www.getacoder.com/
http://contractedwork.com/
http://www.eworkmarkets.com/
http://Drupalancers.com
http://drupal.org/forum/51
PHP: http://www.php-editors.com/forums/forumdisplay.php?f=25
http://www.elance.com
CMS: http://www.freelancecms.com
http://www.ifreelance.com