http://www.google.co.nz/logos/2011/womensday11-hp.jpg

http://www.google.com.au/events/iwd2011

And http://www.google.co.nz/events/iwd2011/

Most of the readers celebrate it tomorrow after 2+something hours :)

https://sites.google.com/site/internationalwomensday2011/home

Google Street View's Pegman becomes Pegwoman on that day
http://maps.gstatic.com/mapfiles/cb/mod_cb_easter_eggs/woman_peg/woman_peg_000.png

http://www.baidu.com/img/baidu_logo_jr_20110308_fnjslogo_a9269900c8ee7c388ceb95f66442d4bd.gif

http://google-latlong.blogspot.com/2011/03/100-years-of-celebrating-women.html

On Bing.com there was 'Another reason to party' pointing to
http://www.bing.com/search?q=international+women%27s+day&form=pgbar1

I.e. on their front page