Pirate Treasure

Ruby 1.9, 175 171 162 153 130 120 117

l=0
gets.scan(/(\w+) (\d+)/){|d,n|l+=n.to_i*?i.to_c**%w[E NE N NW W SW S SE].index(d).quo(2)}
puts'%.3f, %.3f'%l.rect

Python, 158 154 150 chars

p=0j
for s in raw_input().split(','):c,d=s.split();v=sum(dict(N=1j,E=1,S=-1j,W=-1)[x]for x in c);p+=v*int(d)/abs(v)
print'%.3f, %.3f'%(p.real,p.imag)

Haskell (291)

import Text.Printf
d=sqrt(0.5)
f"N"n(x,y)=(x,y+n)
f"S"n(x,y)=(x,y-n)
f"E"n(x,y)=(x+n,y)
f"W"n(x,y)=(x-n,y)
f[a,b]n(x,y)=(s,t)where(s,_)=f[b](d*n)(x,y);(_,t)=f[a](d*n)(x,y)
p[]=(0,0)
p(a:b:c)=f a(read b::Float)$p c
s(a,b)=printf"%.3f, %.3f"a b
main=getLine>>=putStrLn.s.p.words.filter(/=',')