In some consulting work I'm doing, I've been digging in deep, trying to learn everything about the mobile payments marketplace. Most of my research has revolved around SMS-based transactions (rather than WAP) because of the low barriers for the person paying (i.e. not having to sign up for any services), but I've been paying closer and closer attention to the more sophisticated new solutions lately because the 50% cut mobile carriers take to process your SMS-based transaction is way too steep for my client to take part in.
Anyway, at this year's CTIA conference there has been a lot unveiled that adds to the current cache of options. MocoNews has the best coverage of these new options here. I'm certainly reading this carefully.