I think it's worth pointing out that there's a bit more to it all than this and any ETL/BI developers would be wise to have Talend's portfolio of products (open source or Commercial open source) on their radar. In particular there are a couple of interesting distinctions - Talend, like others in similar spaces (check out Bonitasoft if you are interested in BPM) use the Eclipse IDE as the basis for teh interface, hence there is a very easy learning curve when moving between systems and extensibility comes as a given. Second thing and this is a love it or hate it one touched on in the article: Talend OS is a java code generator (they do also have a perl engine but it lacks of few of the transformations as standard) so any workflow you construct actually generates java code - code which you can (unless you loathe java) inspect, tweak, enhance, debug etc as well as which you can of course compile into a standalone executable that can be deployed as a simple jar file to any system with a JRE, no other ETL elements are required nor indeed need there be any footprint at all of the Talend product on the runtime system. Peer support is fairly good and the product has a neatness and transparency about it which makes it very accessible (as well as being free for the Open Studio variety, natch).

Mark