I tried updating to the latest release of Mylyn through the update manager and I encountered the following error:
"Cannot find a solution satisfying the following requirements org.eclipse.swt [3.4.0.v3448f]."
This is how I fixed it:
1) Installed the Eclipse Platform SDK and Eclipse SDK.
2) Restarted Eclipse
3) Added the update site: http://download.eclipse.org/tools/mylyn/update/e3.4 (for some reason it disappeared)
4) Ran an update on all Mylyn Features and Mylyn Integration components (I don't need Mylyn Plug-in Development)
5) Restart Eclipse
Go to http://www.eclipse.org/mylyn/new/ for what's new in Mylyn 3.1.