You probably already know this but, as they say, it depends on your market - some parts of the world have a healthy ecosystem of WAP browser-enabled phones with lots of people using that as their sole means of net access, so a WML based site is a must if you want to provide content to the masses in those cases.
That aside, with the iPhone now the most popular handset in the US [arstechnica.com] - that's right, most popular handset, not smartphone(!) - I totally agree. One of the MAJOR selling points of the iPhone, that we take for granted now, was that it had a web browser that did what no other phone had gotten quite right yet: providing a meaningful mobile web experience on websites that were originally built for a desktop browser.
Since then it's become a virtual standard for smartphones to have this capability. From this (back to the OP) interest in what people would call traditional mobile web development (WML, etc) has dwindled. HOWEVER it's a mistake to think that one can just make a website however they would normally and then walk away thinking you're set for mobile browsers. Flash support, variations in video playback capabilities and other important differences mean there is a new style of mobile web development out there (which is really a riff on current, modern desktop web development) - that of graceful degradation for mobile (not sure if I'm using the right words there, but you get the point :) )
SO. I bet there IS interest out there on that last point. So here's a few tips off the top of my head before I've had my coffee: Make sure your FLASH content has alternative content (goes without saying for SEO), but realize now that mobile users are going to actually SEE this content, so make it snappy. Flash embedded videos won't be playable either, so provide embedded videos as alternative content. So, forum denizens, can you add to my list of tips for modern mobile web development?
Lastly, to the point of mobile commerce, it's coming. Right now a mobile presence is generally most important for being part of the research effort that is performed leading up to purchase (which may be done in person, by computer or by phone). Not being considered during the research effort because you are not accessible from a mobile device means you could lose out on the sale that will eventually occur. So it's important now but you're not going to see alot of transactions from mobiles- just alot of transactions resulting FROM mobile research after the fact on separate devices (anyone want to talk about good ways to track that?).
Eventually, soon, we will get to the point where mobile commerce takes over traditional ecommerce and this discussion will be moot. How soon? Well be sure to review Morgan Stanley's 2009 Economy and Internet Trends [morganstanley.com] research presentation - starting on about slide 28. BTW this presentation is also helpful for converting mobile naysayers- it's tough to walk away from that presentation not feeling that mobile is well on it's way to taking over. It's just a matter of time.