Seems Google is not going to sit quite. Just few months ago Google introduced faster viewing of online PDF's in browsers. Now they have come up with another new features added into the Gmail which supports viewing of TIFF and Microsoft Powerpoint formats too. Earlier there is a "view as Slideshow" option for all the Ppts but now, with the inclusion of these cool features users no longer have to save the files into their computer nor they have to buy and install any software to do so. Just they can directly view them in the browser itself.
Also, users are relieved from the hassles of installing a Flash plugin on their browser. Some additional features like:
1) zoom in and out
2) Select text to copy and paste
3) Print the presentation to a PDF doc
are also included in the roll out of these new features.