Will iPhone OS 4.0 fully support SLS?

I think its a little too early to know for sure, but one would sure as **** hope! I would imagine that details should be coming out soon now that developers will have access to the SDK. I will be a very happy man if this is true (no reason it shouldnt be).

Your question – "is OS 4.0 also fully compatible with SLS?" – is vague. Would you please enumerate specific areas of incompatibility?

Incompatibilities like: push email, push calendars/invitations, and address book server.

I don't know if I'll be more freaked out by learning that the new iphone OS won't support SLS push mail, or when I found out Santa wasn't real.

After getting rid of Exchange server and implementing a Snow Leopard Server we thought we had made a giant step forward... but after 3 months we were extremely disappointed with the lack of supporting pushmail, ical, address book server. Unbelievable.

For address book there is a superb nearly free of charge alternative, with the same name. But for the rest I think it just will not happen.

Apple wants us to use (read $buy$) mobile me for push.
Nowhere Apple mentions something about push for the iPhone with Snow Leopard Server.

I would really recommend Kerio Mail Server as all-in-one replacement, installed on a normal OSX machine.

The good news is CardDAV connector at the iOS4 present and fully working with SLS.
But push still doesn't work, unfortunatly.

Really? You didn't get Push Notifications to work? You should check your service logs then.

Push Notification of my SLS working well, it's push mail's to all Apple Mail App users.
But iPhone 3g with fresh installed iOS4 doesn't recieve e-mail instantly, push doesn't work for iPhone with iOS4 😟

Maybe it is a limitation of the iPhone 3G. I was receiving emails instantly with OS 3.x.x. I noticed this with limited testing in the office, when someone sent me a message I hear their mail client send the email and my phone instantly had that message. I'd have to do further testing.

What kind of limitation do you mean? Push mail on the iPhone Mail working well since 3nd version iPhoneOS, but not with case when Mail server is SLS.
Are you sure about having instant pushed mail to your iPhone that exactly was sending from SLS mail server. I mean may be you are wrong and that was not from your SLS mail account but from yours any really push supported e-mail acount like Gmail, MobileMe or Exchange?

You are absolutely correct, it is not being pushed, the imap connection is just making it seem as such.

There are currently with iPhone OS 3, three missing features most people would list with regards to working with SLS.

1. Issuing iCal invites on the iPhone
2. Using CardDAV (aka. AddressBook Server)
3. Proper working push support

While it was not specifically talked about during either the WWDC keynote, or the previous iPhone OS 4 announcement (now of course called iOS4), there was a slide shown during the original iPhone OS 4 accouncement which showed that it was going to include the ability to invite people to meetings via iCal (CalDAV) accounts, and that CardDAV was also going be supported. I do not remember Push being shown but that does not mean it will not be fixed.

Heres the slide in question…

!http://img.skitch.com/20100609-qwrku4kj7wapphhbxcg6i6xmjc.png!