Managing vim plugins has always been a hassle. Until pathogen came along. If you are using vim with quite a few vim plugins, then you should be using pathogen, if you are not, you are seriously depriving yourself of sanity. No, seriously. You should.
So, I assume you are also versioning your dotvim directory, like on github or bitbucket with git or mercurial respectively. If you are not, then you should. You really really should. If you are going to ask why, go ahead, I will refer to you here on as the douche-bag.
If your answer was no to both of the above, you better get the hell out of here before I get my lawn mowers.
Ok, If you tried to version your dotvim directory, but the plugin directories inside pathogen's bundle directory are repositories themselves, you won't be very happy. You either have to version all the .git and .hg and what not version directories from the plugins, or you just have to ignore them all and forgo versioning for individual plugins. But if you chose the latter, in which case versioning your dotvim will be easy, updating your plugins is a serious pain.
So, recently, http://vim-scripts.org came up and so did scripts like vundle and vim-update-bundles, as listed on the tools page on http://vim-scripts.org. These let you list the plugins you use in your vimrc file and they take care of keeping them up to date. The advantage is that you can version your dotvim directory, and wherever you clone it, you can just run the script used and all your plugins are set up, the latest versions of them, just like that. Awesome!
Vimpire isn't much different from those tools. In fact, it is very similar to vim-update-bundles in functionality, but there are 2 main differences. First off, it is written in python. I won't spell out the implications of that. But, it is ruby-less. Second, it supports hg. Yay! So, you can get plugins not just from git, but also from hg.
How to set it up and how to use it can be seen on the bitbucket page, via the README file.
Hosted at http://bitbucket.org/sharat87/vimpire/src
Please note that this is still beta. Tested on windows 7. I am waiting to get back to my love, ubuntu, but until then, no idea if it works on unix like machines.
Update: The latest version works perfectly with ubuntu too!