I may be late to the party on this one, but I’ve just noticed it and I think it’s cool.
If you search Google for certain sites which are themselves searchable, you’ll get an inline search box right in your Google results.
So, searching for “wikipedia” gives you:
It works for Urban Dictionary too..
Using the search box doesn’t take you directly to the results, but to another Google page with an appropriate “site:” keyword added, so Google still get their advert imprints.
Nice.
Pfft, it’s been like that for ages!