My recent posts don't seem to ever update, the list looks the same now as it did at 7:30 this morning (it 2:20 PM now).
Yes it seems this behavior is not all that uncommon although for me at least at the moment the current list seems only a bit over an hour behind.
To clarify, there are a number of different "recent posts" lists that people may be referring to. These probably differ from one site to another and here I'm specifically talking about how these are listed on the GalCiv2 site.
First off if you come in via www.galciv2.com then there is a Recents Posts box along the left margin. I think this is the one that Captain Yar is refering to because the latest post I see there at the moment is one from 9AM forum time this morning. This isn't the list I usually look at.
I usually go directly to forums.galciv2.com which is the same as goind to www.galciv2.com and pressing the Forums button in the left margin near the top of the page. Anyway once at forums.galciv2.com you see the Category list showing the forums and subforums along with the ten most recent posts at the bottom of the page. This list also has a tendency to get somewhat out of date but currently the most recent listed here is from 13:19 forum time (about an hour and a half old).
To actually get the most current "recent posts" you click on the "More Recent Posts" link at the bottom of the page that takes you to the first page (50 per page) of the current Recent post list (http://forums.galciv2.com/recent). The most recent post listed here is from 14:44 (only 5 minutes old). This is the most accurate place to view the "recent posts". This list goes back 72 hours and usually consists of 3 to 4 pages of 50 threads per page.
AS far as Impluse being the most active, it probably is only natural since it's a new product that cuts across all of SD's products. I guess it is a way to "advertise" Impluse but given that it's to be the future upgrade mechanism for GalCiv II it does have some relevence in the GalCiv2 site and perhaps legitimately belongs in the list of recent posts on the GalCiv2 site. However I don't think the same thing can honestly be said for the OTF and it's subforums.