Currently we are advising a large university on their DNN implementation. They are using portals for each of their faculties and some other sections which they feel needs to be in its own portal.

The one problem is that the core search doesn't seem to allow searching across portals, so obviously a custom module needs to be developed or something else needs to be done to allow for searching and returning results from any portal? Am I right?

Another issue, DNN now has the sitemap.aspx page, but this only returns pages for the main portal and not any other portal pages. Am I missing something here because this seems like a major flaw. They have over 11 000 tabs across all portals, however the main portal sitemap.aspx xml result which could have helped me "crawl" the entire site across all portals cannot be accessed. There doesn't seem to be a sitemap.aspx created per portal either...

I have used the Venexus Search module for a scenario just like you described.   The great thing is that it is a spider so you can crawl any site and include it in the results.

http://www.venexus.com/Store/tabid/55/agentType/View/PropertyID/1/Default.aspx

Stuart