Festivus said:Do not forget that the current DDM rules and miniatures (the bulk of them at least) will become obsolete when the new edition comes out. If you buy lots of older DDM miniatures and want to use some of the newer set they will likely be incompatible.
So Fourth Edition will be a new rule set based on d20, but not remotely compatible. What’s that mean for the minis game? Effectively, this is D&D Minis 2.0 as well. Starting with Dungeons of Dread in April of 2008, D&D Minis sets will use Fourth Edition rules. According to Slavicsek, “All your plastic will still be usable, but your stat cards will need to be updated.” However, you’ll be able to get updated stat cards for free on Wizards’ website for Unhallowed and the sets printed since. In addition, there will be a sort of all-star set of updated cards available for download that will include updated stats for the figs getting the most tournament play. And of course, there’s always room for re-releasing popular figs in post-Fourth expansions of the future.
Festivus said:Do not forget that the current DDM rules and miniatures (the bulk of them at least) will become obsolete when the new edition comes out. If you buy lots of older DDM miniatures and want to use some of the newer set they will likely be incompatible.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.