Ahh, interesting post from GammaJammer above demonstrating peoples perceptions about this type of role!
My thoughts on the role (1985 - 94 derivatives broker/analyst/trader, 1994-5 MSc in IT, 1995 to date, desk developer)
The role is
1) Common sense (if you don't know then say so, don't bulls**t etc)
2) 30% business knowledge (how are bonds/options priced etc)
3) 30% IT knowledge (programming + appreciation of the bigger IT picture)
4) 30% getting on with people . . . a) traders b) network/support c) IT programmers
Get interviewed by the business & they're looking for 1 and 3a
Get interviewed by IT & they're looking for 1 and 2
Given that you're a competant programmer and have a broad business knowledge (an atm option has a delta of 50%, price of a bond goes up so yield goes down etc)
actual role imho is all about 1) & 4).