Hmm.. I'm not seeing a 'significant' market for a 'mini-exchange' that would encourage MSFT to build a product.
I suppose there are three non-excluseive software enviornments Microsoft targets: Home Users, Professional Users and Developers. (Yes, corporate accounts too and backoffices, but that's not what we're talking about)
Home Users would have absolutly zero use for a mini-exchange. POP3 and SMTP? That assumes they will be sending/recieving emails from their local network, which assumes:
1) Static IP (or no-ip.com)
2) Domain Name
3) Modification of MX Record
4) Hopefully a firewall of some sort.
Let's work on getting the home user to run the windows update first.
In the office enviornment this subject is a moot. Being in an 'office' assumes the company would be willing to right off at least the 500 bucks for SBS which comes with exchange.
For the developers: There is no real reason for any Microsoft Developer NOT to have this software, if not a full fledged copy of exchange then SBS. If I remember correctly, my VS.net came with a developer copy of exchange. If you're a student you can get the stuff super cheap at places like www.gradware.com. And like I mentioned before, if you develop products for clients as a side job, you can get the Action Pack. (If your really well off, the MSDN universal is worth its weight in gold)
But I've blathered alot without helping lars:
Lars, what I've done in the past is:
1) Sign up for a yahoo mail account
2) Download Intellisync from Yahoo to your computers
Now you can run Intellisync every day (I think you might even be able to do a command line to have it execute on a schedule) Intellisync will update the yahoo('Public') calendar/contacts/tasks with your data, as well as intigrate any new added items into outlook. The net result is your oulook contacts/calendar/tasks are universally updated.
The down side of this is you need a separate account for each 'public calendar'. But why would you need more than one?
Hope that helps.
P.S. As for 'reverse engineering' Sharepoint/hotmail protocols, Sharepoint loads its 'outlook data' from an exchange server - but lars doesnt have exchange, if he did this thread wouldnt exist. I'm not sure what backend hotmail runs off of, but again, if he HAD that backend, he wouldn need to ask us.
P.S.S As for hotmail http protocols, I believe they use WebDav - but don't quote me on that.