It appears that Nokia is using the N900 as a test bed / developer device to get it ready to ship officially on a future phone. There will not be an official commercial release of Meego for the N900. There is a group of people, including some who work for Nokia & work on Meego, working to release Meego for the N900. One of the big issues is that quite a few components of Maemo & now Meego are closed source apps, binary blobs & various bits licensed from other companies.

This has been a MAJOR issue with trying to create community supported versions of Maemo. Would you want to run Meego on your N900 if it didn't support Flash, phone functionality, wireless, bluetooth, etc. Reverse engineering chips in order to write drivers for them is a decidedly non-trivial task. Until Nokia makes a clear commitment to open up components that are currently closed, I am highly, highly skeptical that we will ever see a community supported version of Meego for the N900 that any regular user would want to run.