A search for search engine roundtable in the Google UK, brings up the 8, as opposed to 4, Sitelinks. For me, the same search at google.com or google.co.uk in Firefox, returns only 4 Sitelinks. Here is a picture of both:
And now when I login into Google Webmaster Tools and click on "Sitelinks" within the links section, I am able to manage those Sitelinks from showing up.
That is one of many new features announced by Google yesterday, as part of a Google Webmaster Tools update. Tamar will have forum reaction about that update later today.
It appears that many folks still do not see the 8 Sitelinks as of this time. I suspect by next week many more will begin seeing it and many more forum threads will pop up asking about them.
Forum discussion at DigitalPoint Forums.