PS. I agree with Jörg that a convenient way to keep the old data directory when upgrading the IPT would be cute.

This is indeed the case.  We will aim wherever possible to make upgrading as simple as it can be.  
For bug fix releases, such as this snapshot, with no structural change the data directory can be migrated directly.   In future releases, we might require a "one time" migration task be run.  I anticipate the first one being required when the DwC standard is ratified.

if you look into your ipt.properties file you can modify the following settings:

dataDir=${ipt.datadir}
registryUrl=${ipt.registry.url}

the dataDir should be an absolute path pointing to your data dir (defaults to the ipt webapp data subfolder).
the registry URL can point to a development registry - unfortunately the extensions and vocabs currently dont use this setting, only the UDDI style registration of resources and organisations. We will make sure that the IPT uses this setting also for the extension registration, so you can easily point it to an alternative extension site for testing.


markus