A remix made by taking two different songs, usually by 2 seperate artists, and combining them into one.
Closer in da club (Nine Inch Nails: Closer, combined with 50 cents Up in da club)
I've seen it in software to describe combining services from two sources to create a new thing. A typical software mash-up is to use Google maps with something else to produce maps that pinpoint something. For example, Housingmaps.com lets you click an icon on a Google map for information about the housing market in the area you click. Or this :
Mashing Up Google Maps with Wikipedia Articles(Another time we'll tackle the -pedia suffix.)
Google Maps, now integrated with Google Local, offers a lot of information about local merchants, but these detailed results typically don't include "overview" information about locations. Wikipedia, by contrast, has great general-information articles about thousands of places throughout the world.
A new service called Placeopedia maps geographic locations in Wikipedia articles onto Google Maps. It's a great feature that bolsters both services.
So, nothing new here with mash-up per se. Paul McFedries finds a cite (in the musical sense) from 1999.
Today, though, I found an instance (new in my experience) of using mash up in a more generic, non-media sense:
Sundaresan was a student of Milos Konapasik (I might have the spelling wrong) who taught textiles at Georgia Tech and worked at Software Arts to create TK!Solver because of the need to solve complex equations. With all the attention focused on glitzy bio stuff it's good to remember that there are other cross-disciplinary opportunities such as mashing up textiles and computing.I poked around a little to see if I could find other such uses, but the majority of uses (all I could find, anyway), were referring to either music or computer services. So maybe this is a term starting to break away from its original, somewhat specific meaning.