Middleware was
the hottest concept in
1998 in the business and industry application software industry. During
1999 the term was replaced by a
TLA:
EAI, or
Enterprise Application Integration. Just like
WoOS mentions in his w/u above, middleware focused on a pretty
low level of intergation -
protocols and
data integration. EAI brought this to a higher level by trying to integrate the
business processes rather than pure
data shoveling. You can charge a lot more
integrating a companys business processes than just its data.
This year, the hot topic in business integration is online marketplaces, such as mySAP.com and those created by Ariba and other high profile players and software vendors.
Examples of middleware/EAI products: MQSeries by IBM, WebMethods (former Active Link from Active Software) NEON from New Era Of Networks, AmTrix from Viewlocity. These differ alot in terms of what comes out-of-the-box and I cannot recommend buying any of them if you don't have a big pile of money to lose.