I took delivery of my 2008 M3 on 21 April. It was shipped with Nav 2007.2. Knowing that Nav 2008.1 was available, I asked the dealer for the current DVD, and I received it 2 weeks later, at no charge. Incidentally, the build date should appear on a decal inside the door jamb on the drivers door.

I should finally be back home in 2 or 3 more days and want to check this out since I've had various map issues during a month of 4K driving. My build date if April according to the service data ceneter described earlier in this threadd.
How do you find out what DVD version you have? I have not wanted to eject mine during the trip fearing I might get something wrong and lose nav for the remainder of the trip.
I'm also curious if the dealer gave you static about this. Did you go through your salesperson or the manager or service?

I asked my service rep about a software upgrade and his line was that upgrades have been known to create more problems than they solve.

:bustingup just the oposite is true.

I have not been able to determine the DVD version without pulling the factory disc and checking the label. None of the "hidden menus" in the nav system pull up the version (at least in NAV Pro). Scanning the disc in a computer using the search function does not display a date, either.
There was no problem from the dealer when I asked for the most current disc. I simply told the salesman I knew a newer version was available; he checked with the service department, and they confirmed it was available but their copies had not yet arrived.

Finally home, I took out the DVD and saw 2008.1 So the problems encountered during my 3.5K tour were present even though I had the latest maps from NavTeq that BMW provides.

When does the next one come out? How often do these upgrades come out? Is there a way to check online what the next map covers so I can determine if it is worth the $200?

It may not be the map software, but the operating system software. I would describe the problem(s) to the dealer, and ask if updates to the OS are available. A family member had problems with his 335i which were traced to Progman, the operating system for the car. The dealer updated the software at no charge.