I would love to think writing this post would settle the confusion once and for all, but I'm sure it won't.
The timezone used inside EVE is the same timezone as used by Iceland itself. That timezone is 'Greenwich Mean Time' (GMT). Unlike many countries around the world, Iceland itself does not have a timezone change in summer. This means that for five month of the year Iceland, the UK and EVE are on the same time and for seven months through summer the UK is an hour ahead. During those seven months Iceland and EVE still run on GMT and the UK is on British Summer Time (BST).
Throughout my entire time playing EVE I am regularly stunned at how the above information is completely misunderstood by people who should know better. Usually it is on the forums during a period of extended maintenance. CCP will often have a message saying the servers will be back at 15:00 GMT and almost like clockwork someone will post at 15:00 BST (14:00 GMT) asking where the servers are.
It is usually at that point someone starts an argument about EVE running on Coordinated Universal Time (UTC) and how during the summer GMT moves forward an hour. The confusion here stems from the incorrect belief that a given timezone can have its time adjusted by an hour. This misconception is caused by people physically having to change the time on their clocks and watches twice per year. What is happening here is not the time in GMT being moved forwards or backwards an hour; what is happening is the country they live in has switched its timezone. In the UK we move from GMT to BST and back. In east coast USA they move from EST (GMT-5) to EDT (GMT-4) and back.
The only difference between UTC and GMT is that UTC has a very strict scientific definition which covers leap-seconds. This means that it is possible for UTC and GMT to differ, but this difference is measured in fractions of a second, not an hour.
So, I hope this clears up and confusion although I'm sure it won't.