A wild guess, well... sort of:
If you're a considered "trusted news provider" you get instant coffee... erhm... frequent udates.
If you're considered a "serious news provider" but haven't been fully "vetted" yet, you get the 7 day lag.
If you're not yet considered a "serious news provider" your home page may be updated but your stories may not rank.
And of course, if you're on the "superfresh" whitelist, like facebook, twitter, etc you get instant updates.
The rest of the sites out there... well, that's just web sites. Not "fresh content". So, they're subjected to the full algo, as usual. Although, with all the fresh content coming in Google is currently pretty slow for "normal" new content. So, you may also have a multiple-algo Google [webmasterworld.com]