I've been using it off and on for about a month, and haven't found any way to add waypoints, but I hadn't thought to look for them until I read your note. Garmin Mobile has a free trial. I'd encourage you to try it for yourself.
I typically only use waypoints for longer trips, and for those I use a laptop and Delorme Street Atlas.
I purchased GM for my Storm after I used up my trial. There is a function on my retail GM version called Mobile Manager that allows me to find locations online thru my PC then add them to my online Mobile Manager account. The GM app on my Storm then can access this online account and download those locations. So, in terms of a waypoint, I can route to each individual saved location. I haven't found a way to include the downloaded location in the middle of a route like a true waypoint but once I arrive at a location I simply route to the next location.
Additionally, the GM app will allow me to upload a location to the online mobile manager account for future use.
