Carbon Copy Cloner was recently updated to v3.5, and is no longer donationware. CCC v3.5 is now a commercial app, with a cost of $39.95 per license.
You can still download Carbon Copy Cloner v3.4.6 from bombich.com, and use it without a license, however v3.5 is required for OS X 10.8 compatibility. The download page states that v3.4.6 is only compatible with OS X 10.4 and 10.5, however we’ve been using it with OS X 10.6 and 10.7 for quite a while without any issues.
If you have an existing Carbon Copy Cloner backup strategy in place, be mindful about updating to the latest version when prompted by CCC’s auto-updater. If you update to v3.5.x, it’ll only run in demo mode for 30 days before requiring the purchase of a license.