“Gu　Gu　Ru” in Romaji or “ã‚°ã‚°ã‚‹” in Japanese kana, probably coined by someone, is somewhat abbreviated word for the verb Google, which often means “to search” within the context of English.  The first two vowels “Gu Gu” are taken from the Romaji (or kana) expression of Guu Gu Ru (or グーグル） for the word “Google.” The last vowel “Ru” or ã‚‹ is then attached to them to make it so called Ru-Verb.
Despite Yahoo’s dominance of Japan’s search engine market, I am finding the expression　”Gu　Gu　Ru” or ã‚°ã‚°ã‚‹ getting popular around here.  The technorati chart also shows it is spreading, if not rapidly:
Posts that contain ã‚°ã‚°ã‚‹ per day for the last 360 days.
Hatena keyword also explains how /when to use this new word “Gu Gu Ru” (ã‚°ã‚°ã‚‹): In Japanese.
NetRating also reports Google Japan users increased by 31% over the year (report in Japanese), whereas yahoo 14% and rakuten 9% were not that high during the same period.
Update: Here I’ve found the mixi community called “Gu Gu tte Iko!” (obviously in Japanese) with a membership of 9,807 as of 2006/06/26.