I have created a few websites over the past few months and all have been indexed with very good SERPs. I simply add a temporary link on my established 12 year old website and the new website is indexed within a few days.
Whatever this sandbox is ( if it even exists) it is obviously reserved for sites that trip other unknown filters as a result of dubious SEO tactics. I think the way to avoid it is to just to not worry about SEO, compose content naturally and have one inbound link from a trusted site.
[edited by: tedster at 11:35 pm (utc) on Feb. 17, 2007]
[edit reason] fix quote box [/edit]