As of today, Myriad's Dalvik virtual machine can run any Android application on the Maemo-based Nokia N900, with other platforms to follow soon.
The idea is to get manufacturers to preinstall Alien Dalvik, as the company calls its virtual machine, or licence the VM to developers who can bundle it with their applications.
It enables an unmodified Android app to be sold as a MeeGo app, complete with installer and native icon, rather than trying to port apps to competing platforms - making every smartphone an Android-compatible smartphone (except the iPhone of course).
Given Dalvik's Java heritage it's not very surprising that a portable VM is possible. Android applications are compiled into byte code that runs in a virtual machine, even on Android devices, so porting that virtual machine to another operating system shouldn't be a huge challenge. Myriad appears to have made a decent job of it.
Right now Alien Dalvik is limited to the Meamo platform, though MeeGo will come very soon and there's nothing (except Apple's obstructiveness) to prevent the emulator being ported to other platforms, which could make Android the only platform worth developing for.
Except that we've been here before - Java was supposed to work this way, but lacked key functionality, and Java followed numerous virtualised programming environments that were supposed to nullify platform dependencies. Dalvik is very functional, but it's hard to imagine it replacing native development.
Still, as a wrapper for those who don't want to port their applications it makes sense, especially if the performance remains so directly comparable to native apps. Alien Dalvik might not render other platforms obsolete - in fact it could help them by ensuring the most popular Android apps are rapidly made available across the board. ®