Legacy rails apps + ruby gems

There seems to be some major issues with working with both Rails 3 and Rails 2.xx versions on same box/ruby install.

When going back to work with some 2.3 Rails apps new versions of Rubygems causes havoc with gem loading.

Not sure there is anyway to have multiple verisons of rubygems installed, installing one version appears to wipe out the existing version. Since latest versions cannot work with Rails 2.3 - see issues like

    NoMethodError: undefined method `name' for "actionmailer":String

Left with no choice but to revert, but then what impact does this have on Rails 3 apps

Resolution : For 2.3.x revert gems back to 1.6 .   :   gem update --system 1.6.2