I think the most important thing is your audience, and whether the name fits the content. I'll compare Huffington Post and Fark.com, not entirely comparable niches but good examples of different naming paradigms and audiences.
Huffington Post sounds like a newspaper. They're trying to be a newspaper (less the paper). You see the name and it sounds like a reliable institution, you can infer that it is infact a news source. If someone gave you an article from Huffington Post you might assume it's just another periodical news thing; you're supposed to.
Fark.com however is a silly headline site/news aggregation, their whole market is in being silly and moderately naughty. What usually "gets" people when the first hear the name is that it sounds like the F-word. It's a little inappropriate, it's silly, it requires more reading in to figure out what it's all about. And that's what it attracts.
If what you want is a simple news site, people should probably be able to infer that from the domain and name of the business. If you want people to look more into it a more whimsical name might be okay, but they should still be able to tell what it is from finding the site.
Twitter and Google are great examples of whimsical but not strictly news related sites; their weird names are fine because they're defining a service (though Google has grown well beyond one service). I'd say it's different if it's "just" a news site though, and hence why most news sites still sound, well, newsy. If I'm just reading one article and finding it from a Google search, I'll trust Newspapername.com, but if I'm going to be using a service and making an account whimsicalname.com might be appealing as well.