I think it depends on your market. If you're aiming for mass-market consumers (i.e. not the people who are reading this comment ;), then .com is pretty important, since many folks don't even know there are other TLDs out there. This is especially true if there's a competitor with the .com -- because lots of people are going to just type your name directly into Google or the search bar and hit enter, and if you're not #1 for your name, you're in trouble.
If you're building something that's targeting our community (hackers, programmers, etc.), there's a lot more flexibility since we "get it" ... I'll just as easily find you if it's .io, .cc, or something more obscure like domai.nr, etc.
I bought a .se domain for a project of mine. In Google Webmaster tools the geographic target is set to Sweden with no way (that I saw) to change it. I got very limited traffic from natural search.
I recently bought a .com domain for the same project and I am already seeing an increase in natural search.
I mean why should a smart search engine like Google limit a TLD to a particular region. Especially since squatters buy good .com domains and charge premium prices. They of all people should know the difficulties of finding relevant domains.
If you're building something that's targeting our community (hackers, programmers, etc.), there's a lot more flexibility since we "get it" ... I'll just as easily find you if it's .io, .cc, or something more obscure like domai.nr, etc.