Here is a preview of a few of the features that are coming soon to Axure RP Pro.
The first is flow diagrams. There have been many requests to add flow diagramming capabilities (http://axure.com/CS/forums/thread/267.aspx) to Axure RP. Currently, to include flow diagrams in the prototypes and specifications, Axure RP users have been copying and pasting flow diagrams from diagramming tools like Visio into Axure RP. This feature will allow users to create flow diagrams in Axure RP and creates some opportunities for tighter integration between flow diagrams and wireframes in future releases.

The second is OnPageLoad. This feature is being developed primarily as a means to set dynamic panels states when a page is loaded (http://axure.com/CS/forums/thread/195.aspx). In addition, it sets the stage for setting variables, passing variables from page to page in the prototype, and responding to the variable values.

The third is support for foreign characters in the prototypes. As more and more international customers adopt Axure RP, the need for this feature has increased (http://axure.com/CS/forums/thread/291.aspx). The umlaut issue discussed in that forum post is being fixed in a minor release, but this feature will also support cyrillic, chinese, arabic, etc.

We are targeting a July '06 beta for these features with a release in August. Keep an eye out!