Yes there are two XNA events happening over the weekend of the 21st March.

There is the XNA UK user group event - open to one and all - on the 21st. Venue: iCentrum, Birmingham

Then there is the X48 event -  a codathon over 48hours starting on Friday the 20th March, finishing on the 21st. This event is primarily open to students in games development courses using XNA. See http://www.x48gamecamp.com/ for details. Venue: University of Derby

So to be clear:

The XNA UK bar camp is a show and tell to lasting one day on the 21st March - OPEN TO ALL XNA INTERESTS

The X48 event is a 48hour codathon starting Friday 20th - OPEN TO UNIVERSITY STUDENTS USING XNA

Take your pick - they’re both going to be wild!