gpgkeys: key C927EBE00F1B0520 not found on keyserver [duplicate]

There are two errors in your question, one of them producing the GPG error.

 GPG error: http://toolbelt.herokuapp.com ./
 Release: The following signatures couldn't be verified because the public key is not available:
 NO_PUBKEY C927EBE00F1B0520

This GPG error is not related to Launchpad and as a result the keys cannot be retrieved with launchpad-getkeys. Following the instructions on http://toolbelt.herokuapp.com/linux/readme, you have to add the key with:

wget -q -O - http://toolbelt.herokuapp.com/apt/release.key | apt-key add -

Be aware that external repositories may be unsafe, only add repositories and keys that you really trust.

Failed to fetch http://ppa.launchpad.net/rabbitvcs/ppa/ubuntu/dists/\*\*DISTRIBUTION\*\*/main/binary-i386/Packages.gz 404 Not Found

You've made a mistake in following instructions. Edit /etc/apt/sources.list and replace **DISTRIBUTION** with your actual distribution in lowercase (e.g. oneiric). Here's a command to do this automatically:

sudo sed -i /etc/apt/sources.list "s/\*\*DISTRIBUTION\*\*/$(lsb_release -sc)/"

In the sources.list file replace **DISTRIBUTION** with the actual name of the distribution (in this case lucid).