I wrote a python add-in for MonoDevelop last year. Unfortunately, I have a hard time sticking to a single project and therefore it suffered a bit. However, we are getting ready for feature freeze for MonoDevelop 2.2 and so I kicked my ars in gear to fix a few things.
Namely, the code completion is much more bearable. Most of the other niceties come from general improvement in MonoDevelop over the last year. You can thank the incredibly talented folks that run the project for that.
For readers that don't know what monodevelop-python is about, let me show you a couple of the features quick.
MonoDevelop knows where you are within the file. It
provides a couple drop-down menus to help you jump around in large files.
It knows when you have typed incorrect syntax. The python
add-in will continually check your syntax as you type so you always know
immediately when you have syntax errors. 
Like PyFlakes? So do I, so the add-in will also lint
through common mistakes and underline those in yellow. 
What good is code completion if its limited to your current
file? Seriously, how useless was that before? Well, now, if you
configure the path to your site modules monodevelop will parse those files too
and build a code completion index to help you along. It's great for exploring
API's! Unfortunately, it doesn't yet work well against libraries like pygtk
where most of the data is provided dynamically at runtime from a shared
library. 
There is plenty more to do for this add-in and I hope I can continue to have time to improve it. But life is crazy like that, and you never know. I'm really quite interested in what people use for a debugger in python. I'd like to add one, but if "pdb" is the best that's universally available then I'm not sure how awesome it can get. Go ahead and leave a comment on what you would like to see and what debugger suggestions you have.
Oh, and here is a little screencast displaying what the add-in looks like live.
-- Christian Hergert 2009-08-25