....it is like the mashups are the lightweight cousin of ETL - for display rather than bulk load purposes. It will be interesting to follow and see how ETL tooling and mashup tooling come together at IBM, especially since the both the ETL and mashup tools tools are part of the Data Integration group at IBM....
ETL stands for Extract, Transform & Load and the bulk loading Ukelson mentions is probably a reference to the way ETL runs behind the sceens -- moving data (sometimes in bulk or in batch jobs) from one place to another (often a data warehouse), sometimes massaging it along away. Eventually that data turns up somewhere (on a display or a report) either in detail or as part of a roll-up.
But server-side mashups (often powered by scripting languages like PHP) whose end result is still display-oriented could handle the sorts of roll-ups that might normally be driven off data warehouse queries.
If ETL and mashups are simply dots along the spectrum of integration, what are the others and where do they lie?