Dicebat - 8:43 am on Dec 7, 2011 (gmt 0) [edited by: tedster at 5:05 am (utc) on Dec 8, 2011]
I created another CSE with a different site and every site I do a CSE for will show thumbnails next to snippets provided that the page indexed of course actually has images to pull.
I did some further research and found that these thumbnails can actually be customized in the embedded html generated by the CSE's final step.Google announced this back in 2009 already. [googlecustomsearch.blogspot.com]
The funny thing is I've been creating Custom Search Engines almost daily for the past two years and yesterday was the first time I saw thumb-nailed snippets.
So I guess I answered my own question. This is probably not a Google experiment, but in fact a CSE feature they released 2 years ago.
It would be cool to see these thumbnails next to ALL snippets in Google's main SERPS though. :)
[edited by: tedster at 5:05 am (utc) on Dec 8, 2011]