.....different handsets support different sizes and many handsets will auto resize for the end user anyway. The issue to consider is download size....you want to ensure that the consumer can download them fast (to save on WAP download charges) without compromising on image quality (as many handsets support image zoom and low res will sho up if they zoom in x2 or x3). You'll find that JPGs for mobile are typicallly 30kb in size and video 60 secs (8 to 12fps) converted to 3GPP but you probably want to sell them larger than that as any good mobile content retailer will be auto optimizing the asset on the fly when the end user enages in a WAP session so he/she shouldnt demand that you do all the hard work!
I'd be interested in talking you you about reselling your content over mobile..please hit me up.
Chris, BabeCell
ICQ: 261 131 833
http://www.babecell.com
.:Cash in on Cellular:.