The $99 card works with handhelds: SDIO is increasingly the form factor of choice for handheld devices, whether cellphones (which sometimes opt for mini-SDIO), cameras, or PDAs. Having a Wi-Fi option for those devices that don't offer Wi-Fi built in or through their own card is extremely worthwhile, and the retail price of $99 for the Go Wi-Fi!--love that !--makes this a decent choice, even.
The Socket card uses 802.11g, the faster Wi-Fi standard in common use, although the overall throughput is highly dependent on a device's bus. Still, even if a device can only push 1 Mbps over a 54 Mbps connection, 802.11g ultimately uses less power to move the same bits and occupies a network for less of the time, improving overall throughput.
Socket claims fairly wide support, with drivers for Dell HP, and Palm devices, and Windows Mobile 2003/2003SE and 5.0. They also say that the card supports Windows CE 42/5.0 drivers for embedded devices, which could encompass a fairly large category of equipment. There's a full suite of security support--thank you, Socket--including WPA Enterprise, but it appears its lacking WPA2. This shouldn't be an issue for many customers, although some people may be required to use the stronger AES key available only in WPA2 if they work for the government, or in healthcare or the legal industry.
The system includes a Wi-Fi management program that's sold separately for $25.