Portland, according to a sentiment first started by Seattleites, is a city "that needs an ambition bomb dropped on it." This is, of course, all about perspective. There is, however, a good point in the sentiment. Portland can easily be seen as a slacker town with a large "creative class" (read: getting by, no real job, working on this or that). I like to say: "In Portland, you can have a full-blown meth addiction, a paper route, and own a house." In 2010 that might mean you're in PoFo/TriBePo/Felony Flats/across the Mason-Dixon (82nd Ave), but you own a home in one of the United States' premeir cities.
In its defense, Portland is quite an inclusive city. Places like New York, San Francisco, Los Angeles, and even Seattle, could easily be considered "exclusive." In Portland, if you see a person or group doing something interesting, all you need to to is go up to them and introduce yourself and ask to join in. They will welcome you with open arms. This is far from the case in the other listed cities.
Portland is a lifestyle. People here are wicked smart, fairly outgoing, curious and fun-loving. But entrepreneurs they are not. It's more important to identify with your hobbies and likes than it is to make money off them. This is probably a good thing. People here can be very altruistic. But they can't be bothered to work hard to start a company and grow it. They're more comfortable dreaming big and following half-way through. This sometimes means big things happen. This is partly due to many Portlander's abilities to "self-promote." People love to talk about what they're doing and how hard they do it. You can be a part of it, too! Of this thing I did.
Backpacks and dogs.
There is a large community of smart geeks here, and a few decent tech companies hiring those geeks. But mostly, venture cap doesn't flow through this town.
This post is just a start at my stab at what Portland is... comments welcome.