Will a “coming soon” page negatively impact my site?

Matt's answer:
CUTTS: Remiz Rahnas from Kerala, India asks, “Is it good to put a ‘coming soon’ page for new domains? Google seems to prioritize new domains in SERPs. Will a ‘coming soon’ page stand as a negative for it?” No. I would, you know, I think a “coming soon” page can be pretty smart. I think it’s good for users so that they don’t just end up on a “black hole page” that, you know, it doesn’t resolve or something like that. If you have some content that’s coming out, I don’t think there’s any harm from having a “coming soon” page and then as you get more content you can put that content out there and then when the full site is ready you can have the full site out there. So I wouldn’t worry about, you know, ranking-wise, that being a problem. I think it can be a good thing for users and it can be a good thing for search engines.
by Matt Cutts - Google's Head of Search Quality Team