Apologies for posting an answered question, but an earlier thread contained a very unclear answer.
Problem: You’ve marked all of your seams (if the object is complex and needs them), and now you decide to UV unwrap. But when you go to the UV/Image Editor, you can’t find your UV map in the list of images to show. Maybe it just says ‘Render Result’ and that’s your only option.
Solution: In the UV/Image Editor, the section for selecting your image to show has an ‘F’ button, a ‘+’ button, a folder button, and an ‘X’ button next to the dropdown image selection box. Click the ‘X’ button to unlink the data block, and voila! The UV map shows up.
But I STILL can’t see my UV map!
Be sure that after unwrapping your mesh you kept the 3D View window in Edit Mode with relevant faces selected. If you return to Object Mode, the UV/Image Editor won’t know which UV map to display, and if you don’t have any faces selected it won’t be able to display them.
Please post any other UV mapping visibility issues/solutions so somebody else can stumble on this thread somewhere down the line and find an answer!