I want to be able to update content on one slide and have it show up on my other slides (i have a presentation where there's allot of shared conent and right now I have to cut and paste across the slides). I want to have a function just like in excel where I can have a reference cell in multiple worksheets *update the reference cell info and it updates all other references. Is this possible in powerpoint?
You can do cross-references in Word too (though not quite as easily as in Excel) but it isn't possible to do within a document in Powerpoint.
It is possible to get some of the functionality you're looking for by putting common material on additional master slides and then using those master slides as a base for the display slides. That way, anything that is in the master slide appears in all the display slides based on that master slide. However, then you would have the same material in the same location on every slide that used a given master slide, which might not be what you need.
If it is OK to have the common material in external files then you can insert each piece of content as an object linked to a file that contains that material, as described in Powerpoint 2007 linking to external content. This solution allows the same content to appear in different places in different slides.