SQL Server 2014 packs with a lot of new features like In-memory technologies (Code name Hekaton), buffer pool extension, new cardinality estimation logic, tighter integration with Windows Azure and many more!
Excited? Let's get it!. There are multiple ways you could download SQL Server 2014. You could download the evaluation edition with 180-day trial at TechNet Evaulation Center. The evaluation edition contains all features available for Enterprise edition so you can test all these new features.
If you are MSDN subscriber, all SQL Server 2014 editions are available for download. Once you login to MSDN download page, there is a new link for SQL Server 2014.
Here shows partial list of downloadable images available for SQL Server 2014
Another way to get your hand on SQL Server 2014 is through Windows Azure. It takes only matter of minutes to provision a Windows Azure virtual machine with SQL Server 2014. The Windows Azure virtual machine gallery provides several images contain different version and edition of SQL Server. The picture below shows the selected image for Windows Server 2012 R2 with SQL Server 2014 RTM. If you already a MSDN subscriber, definitely check this option out since there is free monthly Window Azure credits as well as discounted rate.
Traditionally there will be a developer edition for sales (more detail here). Since Microsoft just release SQL Server 2014 today, it may takes some time for any online or physical stores to start selling them.