Apple has released two new betas today for iOS 8 and OS X 10.10, which is the second release for the beta cycle. You can download the updates by going to the App Store on OS X or checking for software updates on iOS.
Apple will be launching both platforms later this year and both bring many new features to the mobile and desktop operating systems. You can take a look at OS X Yosemite here and iOS 8, here, to gain a better understanding of each operating system and what's on offer.
The update for OS X 10.10 does not contain a change log, as noted above, and takes about 15 minutes to install. iOS 8 update contains "bug fixes and improvements", but the specific bugs that are squashed were not listed. Generally speaking, Apple will release a number of betas before the product reaches 'Gold'; this is when Apple will make the updates available to the general population.
As always, pre-release software from Apple (or any other vendor) is intended for testing purposes only and should not be installed on production machines. If you do decided to test out the new builds, let us know if you find anything new in the comments below.