Trying out Merb+DataMapper just now?

[mikong]

The Problem

You may encounter this problem with 0.9.3. As you follow those merb
+datamapper installation tutorials, by the time you run "gem install
merb_datamapper", you might end up with a bunch of gems at version
0.9.3 and a version 0.9.2 merb_datamapper gem (which doesn't play well
with the 0.9.3 brothers).

The (Probable?) Cause

The Merb team just transferred the task of maintaining merb_datamapper
to the DataMapper team. The 0.9.3 version of merb_datamapper has been
uploaded to RubyForge by the DataMapper team last July 30. But you
can't install it, and you'll just get 0.9.2. I thought it was a
RubyForge servers syncing problem but it wasn't. Dan Kubb, one of the
DataMapper developers, suspects that RubyForge might have a protection
mechanism that prevents other RubyForge accounts from providing a gem
of the same name (to prevent new accounts from hi-jacking other gem
projects by simply uploading a fake newer version of a gem). Since
Merb project in RubyForge has a merb_datamapper 0.9.2, it might be the
reason why the 0.9.3 version from DataMapper can't be seen with a gem
install or update.

The Workaround

Just download the merb_datamapper-0.9.3.gem file from RubyForge
(http://rubyforge.org/frs/?group_id=3242&release_id=24312) and run
"gem install merb_datamapper" in the directory where you have the .gem
file.

Or just wait until they fix this, which I hope will be soon.