tatfiend 

Lots of bikes withy hub gears are available currently. Look at the bikes from Civia and Swobo for starters. Also virtually every major manufacturer has at least some bikes with gear hubs including models from Trek, Specialized and Cannondale as well as REI.

None I am aware of available fitted with the SRAM Dual Drive setup unless there is a MTB available with it, the original market it was designed for.

Some folks like gear hubs for commuting or urban bikes for their convenience. Others, such as one poster here, do not care for them. I personally do like them for their ability to shift at a stop and the ability to fit chain protection. Some weight increase but typically less than 2 pounds considering eliminating two derailleurs, the casette freehub and one or more chainrings. I believe the impression of increased weight is due to the weight all being concentrated in the rear of the bike when picking it up.

My LBS has offered me a smoking deal on a NuVinci rear wheel so I am going to try that out shortly. Fitting it to a old 1990 Trek 950 frame which is also suitable for adding an Xtracycle conversion onto for a cargo bike if I decide to go that route. Now the NuVinci hub willl add considerable weight to the bike but I am curious to try the continuously variable gear capability it offers.