Yeah that resolution smoeone mentioned above is correct. Yeah JPG, PNG, probably GIF, probably BMP and PICT, probably TIFF.... but yeah might as well stick with PNG or JPG.
The trick with an iPhone wallpaper is to take advantage of how it's layed out on the screen. It only really shows when the screen is locked, and it shows some user interface elements over the top and bottom edges.. here are acouple pics that illustrate how it's shown:
Only problem is I can't seem to take a screenshot in that mode so i can't figure out exactly how many pixels high have the translucent overlay at the top and bottom.
The trick with an iPhone wallpaper is to take advantage of how it's layed out on the screen. It only really shows when the screen is locked, and it shows some user interface elements over the top and bottom edges.. here are acouple pics that illustrate how it's shown:
http://www.flickr.com/photos/mediahound/848484164/
http://www.flickr.com/photos/fhke/352687304/
http://www.flickr.com/photos/bernardyeo/1844430380/
etc.
Only problem is I can't seem to take a screenshot in that mode so i can't figure out exactly how many pixels high have the translucent overlay at the top and bottom.
if not, guess I might have to make some up...