I often tell people that open source work can help get you experience. I want to relate two concrete examples.
Stan James is the creator of Outfoxed. His work gained some popularity in tech circles and soon Outfoxed began rising in the del.icio.us tags. Our CEO noticed it getting popular and looked into it. After learning about it, he contacted Stan and hired him.
Greg Yardley authors a blog. Through the various channels by which blogs get publicized, our CEO came across it and started reading it. He was impressed with Greg's writings and contacted him, ultimately hiring him.
These are very unconventional hiring methods. These are also key gorilla recruiting methods that can be highly successful. (It has not slipped my mind that googling me brings up many of my JavaRanch postings--which has gotten me some jobs as a book reviewer for some publishers, but that's it.) Don't expect large MNC to employ these tactics as a norm, but people in organizations large and small do look out on the internet and if something you do is visible, you may get noticed.
People who contribute in opensource are always in demand.In India there is a acute shortage of open source programmers.I have seen AOL,Yahoo!,Novel,Mcafee giving ads for months in newspapers for finding the people.
I have also got some assigments due to my site & some of the posts I have made here. Just for record!!
In fact my current company found me through some of the articles I have online on another site & through some of my work online. I also agree that if you're an active member of programmer community, you'd be noticed. Not many companies in India take the trouble though...