I'm working on creating a common navigation experience across two site collections in MOSS 2007. I've looked around for various solutions and haven't found anything that fits. Our navigation is dynamic and driven by a number of factors, including audience targeting. Most of what I've found relates to having static XML and that just won't work for our requirements.

What I'm down to at the moment is just getting a navigation item from site collection A while in the context of site collection B. Are there reasons I shouldn't be able to just open a navigation item from site collection A and gets its audience? Certainly there could be permissions problems on my end, or code related issues, or things that are in my control. What I'm wondering is if there's something inherent to SharePoint that would not allow this. Something I don't have control over which would force me to travel a different path.