As we are heading towards 1.0.5 release we updated the Feature Roadmap page on PowerGUI.org so it lists the features and bugfixes which made their way into the release. (Go to http://PowerGUI.org first if the direct link does not work.)
The biggest improvement is asynchronous work (whenever possible) with the underlying PowerShell system. So we start outputting processes, user accounts, mailboxes, etc. as we start getting them. In 1.0.4 and earlier one had to wait till all of them got received by PowerGUI which could take quite some time.
Other improvements include better toolbars, autosave, etc.
Some of the items in the list are links to the forum threads in which community members found the issues or suggested improvements.
We are still a bit behind in the sense that not all of the items are properly referenced, and the information on the plans behind 1.0.5 is not yet exposed, but we are getting there! Just give us some time to catch up and fully deploy the feature tracking system and this will be the most transparent and community-driven project ever!