If you're doing "deep technology work" in a field that's as relatively new as Hadoop, chances are your name will start to make it out there -- and that you'll start to become known to others in the community, including Cloudera staff, because you're bound to be on IRC, asking questions, submitting patches, going to conferences, etc etc etc. I agree that there are plenty of people who don't really know the technology, but who make a habit of commenting on others' blogs and so on, but those people are pretty easy to spot as soon as you start really talking to them about the technology. (Disclaimer: I work at Cloudera.)
I mean you can see it today if you read blog comments. There is a growing share of people spending their day making flattering pseudo insightful comments on other people's blogs.
And using open source projects for self promotion is very damaging for those projects. The difficulty for many open source projects is that they need maintainers over many years even when the technology isn't the hype of the day any longer. Having self-promoters pass through a project until they got the job they want is a horrible idea.
Also, I'm not sure that it's a smart move on the part of cloudera to actively ask people to hit on their employees. Is that really the best use of their time?