Changes I'd like to see
- support multiple Prism executables to run concurrently. e.g. GMail, GoogleReader, GCal, JIRA could all be apps
- allow the icons to be easily customized for when switching with TAB or adding things to the dock.
Update - many thanks to Dave Brondsema who mentioned in the comments that you can have multiple webapps running with custom icons using the provided bundes from http://wiki.mozilla.org/Prism#Bundles
Though I tried them and they didn't wor for me too well on the Mac (I've not upgraded to Leopard yet :)