Mac OS X's Preview app has come a long way since its humble beginnings as a PDF viewer. AppleInsider reports that in the latest build of Lion, Preview has received a UI overhaul and added some pretty cool new features.
For example, Preview will act as a Microsoft Word, Excel, and PowerPoint viewer. This is one of the smartest things Apple could have done. How many times have you sent a PowerPoint file to someone only to get an email back saying they didn't know how to open it (happens all the time with my friend's grandparents)?
Now when anyone running Mac OS X 10.7 Lion receives an Excel or PowerPoint file, the file will automatically open in Preview if they don't have Office or iWork installed. Of course, they won't be able to edit the Microsoft docs in Preview, but they will be able to view them just like they can view PDFs. Word docs can open in Preview as a viewable file too, but by default they will still open in TextEdit as an editable document.
Other additions to Preview include Full Screen mode; monochromatic, square toolbar buttons; a magnifier loupe tool (like the kind you find in Aperture); expanded PDF annotation tools (including filled text and speech and thought bubbles); and the ability to scan your signature in the Preview app so you can use it to digitally sign documents. I don't know about you, but I always look forward to OS X upgrades not so much for the big features, but for the continued refinements to the OS and its apps as a whole. Judging by the way Lion is shaping up, it won't disappoint.