Rails 3 plugin development - recommended practices?

I have been thinking that there must be some better ways of doing
Rails plugin development than my current approach. currently I tend to
have my plugin in one location as a gem and then link to it from my
Rails 3 app vendor plugins folder with a symlink. Then I have to carry
around the whole Rails 3 app as baggage for development. What is the
better option?

Aren't there some libraries, tools out there specifically to meet this
need? Seems like various plugin developers each have their own setup
for doing this!?

I tend to use RSpec 2 for all my testing needs. How does rspec-rails
fit into this?