Having just come back to Singapore I tried to use my Huawei E180 dongle to connect to SingTel's mobile broadband, but it completely failed in Snow Leopard. Fortunately there's a simple enough fix.
The problem stems from the default Broadband on Mobile application bundled on the virtual CD: when I attempted to connect in Snow Leopard I got a "Failed to find the device" error. Kim Hoong had a great blog post about the problem with an E170 which generated a lot of comments from Singaporeans with similar hardware problems, but these steps worked for me.
First, unplug the modem and if you installed the client software delete the following files:
/Applications/Broadband on Mobile.app/Library/Modem Scripts/HUAWEI* /System/Library/Extensions/Huawei*
Second, go to this excellent MacTalk Australia howto page and download their
MobilePartner.mpkg package about halfway down. Install it.
Third, plug in the E180 modem again. You'll be prompted if you want to install new network hardware, and if you choose yes the Network System Preferences pane will open. Click the first
HUAWEI Mobile connection which has been created and enter
*99# as the telephone number.
Connect, and budda boom! All done!
Here's hoping for their own sake SingTel Mobile get their act together and help people who call them about this issue. Macs are still a minority but especially amongst students here they're rapidly increasing market share.