I think pretty much all of us use emoticons. I started off with ":-)" back in the UK and gradually picked up the Japanese equivalents "^^" upon moving to Japan.
Previously used western emoticons when I first started blogging but as I started to read more and more Japanese blogs and communicate in Japanese through mail, I naturally picked up usage of Japanese emoticons. I discovered that I could express "fake-laughing-in-embarrassment-with-cold-sweat" with the "^^;" emoticon - have no idea how to express that feeling with a western emoticon (if anybody has a link for a western emoticon dictionary then feel free to share.)
I still use both depending on the context. For example when at Amazon and Microsoft, mails to folks at HQ in the US would be riddled with western emoticons. Sending my Vice President (the guy who reports to Jeff Bezos) mails full of (＾ω＾) or (*⌒ー⌒*) would have probably affected my salary ^^;
What do you prefer to use? Do you use both? Do you understand both? Are there emoticons that you reckon we haven't seen before?