If you're looking for an open source integration tool, consider Talend Open Studio. Talend let's you create ETL and other integration processes using a panel-based Eclipse IDE (Galileo). Talend works with many sources and targets including Excel, flat files, XML, and relational databases. When creating processes with Talend, there is a rich library of Components which are packaged objects for transformations and scripting.
Talend generates code, either Java or Perl. I noticed a lag when generating the objects on a laptop or starting Open Studio. One time, this resulted in a strange delimited file preview exception that was corrected when I restarted Open Studio. I have Open Studio configured to run the Generation Engine Initialization routines in the foreground and haven't seen a reoccurence.
I've also had to delete files from the metadata/fileDelimited folder after deleting something from the IDE. Open Studio wouldn't let me re-use the name of a File Delimited. This may be an Eclipse convention, but Eclipse usually prompts you to do a complete delete from the file system.
Look for future posts on implementing Data-as-a-Service with Talend.