We are planning on creating a mobile app for the major smartphones and we will also have a version of our site that is optimized for mobile viewing.
Are you going to/have you created both? Would love to see your apps/sites if you could share!
So far we are planning to go the route of a mobile site. but I do like the idea of both for the major devices. The reason is that you can store some data on the devices. I was thinking this might be useful when doing barcodes on a device for ticket scanning. Rather than hitting the server again the ticket barcode could be saved to the device.
I created a proof of concept using JQtouch which really gives a good look and feel to mobile for IPhone/Ipods. I posted some info and a demo of what we did over here: http://www.tessituranetwork.com/COMMUNITY/forums/t/3496.aspx
I found recently a free book on windows phone 7 development over here http://www.charlespetzold.com/books.html. Another tool i was looking at is MonoTouch for developing iPhone apps using .Net code.