So Rails and Merb are sort of merging in Rails 3.0? Thats how its been described to me anyway. This means that a lot of what made Rails, Rails will now be moved to plug-ins so that it can be more lightweight. HOwever, what are those plug-ins going to be and as a new Rails developer, what are THE must have - and also more mature - plug-ins that a Rails developer should install? Some good examples I can think of might be will\_paginate, ruby\_prof or sqlite3-ruby.