Direct download: PackageManager.sublime-package
The name is quite pretentious, especially considering the meager features at the moment:
* Download .sublime-package files and copy to Installed Packages (non-blocking)
* Uninstall packages by deleting package folder from Packages and .sublime-package file from Installed Packages
* Check for updated versions of packages (blocking)
* Adding repo urls to the database (this might not be working, though)
It's been very little tested and generally hopes for the best: no error checking (not even for an inexistent Installed Packages folder), no proxy support, etc.
What it does is downloading a tip revision as a .zip file from GitHub repositories and performing renaming and copying as needed, so it isn't very smart. If people find it useful, though, I might improve it and eventually move it to the SublimeText org.Warning: It might download harmful files and it might delete files you don't want deleted. Use at your own risk, etc. Hope you like it, though.
Check the readme on the BitBucket page for more info.