Photoshop has been in the English lexicon as a term to edit images for a long time, but the latest version of Adobe's flagship program stretches the canvas of manipulation much further than ever before. Don't worry about the lack of a new interface the new ways to get your project done make this version a must.
The bottom line: Photoshop CS5 greatly expands the toolset that Adobe offers in its flagship product, charting new ways to make image manipulation easier while making older tools work better than before.