In July, Secret Compass are off to cross Europe’s biggest glacier – the Vatnajokull ice cap in Iceland taking on Hvannadalshnúkur (2,109.6 metres), Iceland's tallest Mountain. If anyone has been would be great to hear from you!

There are several company's in Iceland that can provide assistance and guides to cross the glacier and to reach the summit of Hvannadalshnjukur.

Just to name a few:

http://www.trek.is/
http://www.mountainguides.is/
http://www.bergmenn.com/

Also see http://www.safetravel.is/ for various safety related issues.
And http://www.isalp.is/information-in-english.html for the Icelandic Alpine Club.

I have attempted to climb it in June 2010. No technical difficulties, not many crevasses but almost 2000m height gain in one day. Navigation can be tricky above 1600m in poor visibility.
We had to back off due to the extreme winds and snow. The weather factor is crucial as is very exposed point far north.
Good luck and have fun!