How can I tell which is the current salesforce release version my org is running?
Usually you can tell what release (e.g. Winter '14) you are running under by looking at the logo in the top left, but if that has been customised or removed it's not an option. Is there some place in the setup or settings that lets you know what release you are running?
To know the current salesforce release version your org is running -
Option 1: 1.Login Your Org --> SetUp --> Company Information -->Instance --> Take the value of this
2.Open the link --> trust.salesforce.com --> status.salesforce.com --> status button click --> search with above instance --> After it finds the instance result --> click on the link --> Right side it show the Instance Details.
**Option 2 
*Simple, Refresh the screen it shows the logo and image of the release version, Sometimes it will be very fast and cant see the details.