If you own Minecraft and want to create magic away from your PC but lack an Xbox 360, iOS device or have no plan on buying a new phone, there may still be hope. DS modder Smealum has recently unveiled his homebrew Minecraft demo for the handheld.
At the moment it is only possible to add or remove blocks and there is no save function. Smealum does have plans to add more features in the future, including a full level generator. His eventual goal is to get a fully working classic version of the game running on the DS and, if successful, he has said he would like to try adding survival (provided the system can actually support it).
Minecraft DS demo[DS-Scene]