From the horse's mouth, an explanation for the delay: Palm users have been anxiously awaiting software drivers that will support SanDisk's SD Wi-Fi card. SanDisk released a pretty detailed explanation for the repeated delays.
It looks like some people think there are deeper problems at Palm causing delays in the Wi-Fi enablement of Palm devices. You may want to read some of this with a grain of salt seeing as the site is dedicated to Microsoft platforms, but MSMobiles, has done some digging around problems with the Palm platform.