Thanks for sharing (and of course, for the product).

It's not just a matter of HN vs TechCrunch, it was that HN led to TechCrunch and other outlets, as they obviously check (or their friends do) HN to see what the community is talking about.

But it's not surprising HN would have more conversions. More people on HN have Posterous blogs than I imagine in other crowds, and probably moreso compared to the average TechCrunch reader.