Throughout the years Google has always tried to keep the conservative 'Search Engine' Look & Feel. Within the past year wev'e notice many cosmetic changes to google starting with Google Places Integration and now - Google Instant Previews.
Now, when browsing your search results, you will notice a instant preview popup once you hover your mouse over each result.

On one hand, it's nice seeing Google refreshing their user-interface. It's always nice to have a fresh layout.
On the other hand, people involved in PPC marketing campeigns (Adwords) have been voicing concern over the new Preview feature. One argument is that people would see a preview of the site, and not click on the actual link. Another agrument says that once the preview window pops-up, it blocks the view of some ads (being on right side of the screen)

I've noticed that Google isn't operating this feature in 'full-swing' yet. Personally, I've been able to see it from different computer locations.

Lets wait and see what Google has next for us ...