There's free wireless internet at a couple places in Wanchai. Check out the Bridge and Carnegie's, both on Lochart Road a short distance from the Wharney Hotel. I make extensive use of them when I'm in HK since they're both usually almost empty in the afternoon. (I ended up munching on snacks or ordering soft drinks to keep from being a complete freeloader.)

One note: I did see that the wireless network at the Bridge doesn't allow you to send email. (For you geeks out there, they've blocked the SMTP port 25.) This shouldn't be a problem for anyone who uses a web-based email client but it'll cause problems with Outlook Express and similar programs.