David and I teased it earlier this week on MPU 158, but the new 1Password version 4 for Mac was officially launched today. I've been beta testing the App for several weeks and it's a solid update bringing a total redesign and a slew of new features. Among my favorites are iCloud sync, favorites, the ability to securely share passwords, and the built-in security audit. You can read comprehensive reviews from Macworld and MacStories.
The upgrade policy is very generous. 1Password version 4 is a free upgrade to anyone who bought v. 3 through the Mac App Store or anyone who bought v. 4 directly from AgileBits anytime in 2013. If you bought from Agile anytime before 2013 you can upgrade for $24.99. If you're completely new to 1Password, it's currently on sale for $39.99, a 20% discount. I personally recommend the Mac App Store version, but you an also buy directly from AgileBits if you prefer or need a switchers bundle that includes a PC version. Full details are in the AgileBits blog post. You can also buy 1Password for iOS.
Disclosure: 1Password is a sponsor of Mac Power Users