The answer is "yes", but at present there is no documentation for creating new reports. However, reports are based on the ZipTie extensible tools framework as well as BIRT, so it is possible to develop new Report Plugins without changing client or server code.

ZipTie reports are developed using the BIRT Report Designer (http://www.eclipse.org/birt/phoenix/). Reports that rely solely on information in ZipTie's SQL database can be written purely from within the BIRT Report Designer environment. However, reports that need to access information not in the SQL database, for example information stored in the ZED (ZipTie Element Document) need either JavaScript and/or Java code to accomplish at present. These would likely require the ZipTie development environment to be setup (http://docs.ziptie.org/doku.php?id=dev:howto_getziptie).

I can tell from the kind of report you are asking for that it falls within this later category (needing information from the ZED) and therefore will be non-trivial to implement. If you are a Java programmer and don't mind learning from the code, this report can probably be created in a matter of a few days.

Given the new-ness of the reporting framework in ZipTie, I anticipate that I will be making a number of enhancements that will be in the next release of ZipTie that will make creating reports based on information in the ZED easier. However, they still may require JavaScript coding.

The learning curve on BIRT itself I have found quite steep, especially once you get beyond SQL-based reports.

If you want to tackle this report yourself, I'll be happy to provide what support I can through the mailing list or IRC. Otherwise, you can open an enhancement request with details about what the report would contain (including any calculated values) and we will try to get it into the next release. If it can be accomplished before the next release, you will be able to download the report from the ZipForge.

-Brett