Microsoft Exchange and stuff

Entering a small or midsize company here in Norway you will most likely find an Microsoft Exchange server. Now, this is giving FLOSS a challenge. Several challenges actually. The two challenges one will meet first is finding a FLOSS client to connect to the Exchange server. (Paying for closed source plug-ins is not an option! It would just defeat the purpose of using FLOSS.) And secondly the removal of public folders in Exchange 2007. (It is not really removed, but it is hidden to discourage using it).

How is the removal of Public Folders have anything at all to do with FLOSS you might ask. well, it has very much to do with Microsoft pushing SharePoint. SharePoint is Microsoft way of trapping it's customers even tighter into the Microsoft world of document formats, document creation and editing plus document handling and publishing. In other words, SharePoint makes it even harder to break free from the Microsoft lock-in. When Microsoft Exchange is introduced into organisations today the organisations are told that Public Folders are disappearing. Then the sales representative from some Microsoft partner company tell them that the organisations must go the SharePoint way to keep and expand the PublicFolders functionality. (That there are a lot of half truths in what the sales representatives are saying is apparently not important...)

So, what can one to to conquer this using FLOSS? Does there exist systems that will behave transparent for the users giving them the PublicFolders, SharePoint functionality (I'm not claiming the Microsoft technology to be superior in any way, just that it needs to be replaced). If such software exist, and this software performs better than the Microsoft way, please tell me. I would market it where ever I can.