The big - if unsurprising - news in iOS 8.2 may have been Apple Watch support, but the update also includes security fixes.
The iOS issues disclosed by Apple made it possible to intercept SSL/TLS connections (the so-called FREAK vulnerability), allowed an attacker to force a restart by sending a specially crafted SMS to the device, made it potentially possible to execute arbitrary code inserted into the data stream during iCloud Keychain recovery, gave a way to see the home screen of the device even if the device is not activated, and provided paths for malicious apps to gain system privileges or to create folders in trusted locations. Perhaps ironically, the TaiG Jailbreak Team was credited with finding that last issue.
Security Update 2015-002 for Mountain Lion, Mavericks and Yosemite fixes FREAK, along with the iCloud Keychain and the privilege escalation issue as found in iOS.
It also addresses another privilege escalation issue, and a vulnerability that could help attackers overcome address space layout randomisation.
Apple also updated Xcode. Version 6.2 includes a new version of Apache Subversion and a fix for an issue in git that allowed "unexpected files" to be synced from a malicious repository.
The updates are available via the usual mechanisms.