While I have my head in the clouds, I should mention that Vertica has a cloud solution that they manage for you. Not new, but gives some perspective.
With competitive offerings in the $10-20k per terabyte, this is an attractive offer and a great way to try before you invest when you have that much data.
I hear Vertica is a screamer, but I can’t imagine getting sub-second results for 3 TB of data on 3 virtualized servers, for the same reasons I gave in my previous post.

Hi, I just started a blog about Qlikview and have a link to your site in my blogroll.
Maybe you are willing to put a link to my blog at your blog!
Happy Blogging!
Gilles