Toy Problem of the Week

I was raking around on the net and found this problem and coded up a solution. Once we get at least 10 solutions I'll post mine and a link to where I found the problem.
Any language, any libraries (but declare them) allowed. Aim for clarity and conciseness. Assume the input is well formed. Mine is 5 lines of scheme code (6 if we include requiring a library). No calling an "answer" function that "you wrote already and put in an external lib" ;)

Consider the problem of turning a list consisting
of a mix between symbols and non-symbols into a
list of lists of the symbol and its following
non-symbols. That is:

Input:    ({<symbol> <non-symbol>*} ... )
Output:   ((<symbol> (<non-symbol>*)) ...)
Example:     (a 1 2 3 b 4 5 c d 8 9 e)
           -> ((a (1 2 3)) (b (4 5)) (c ()) (d (8 9)) (e ()))

def foo(arr):
  def f(a, c, d):
    if c == len(a):
      return d
    else:
      if 97 <= ord(a[c]) <= 122:
        d.append([a[c],[]])
      else:
        d[-1][1].append(a[c])
      return f(a, c+1, d)
  return f(arr, 0, [])

a = ['a', '1', '2', '3', 'b', '4', '5', 'c', 'd', '8', '9', 'e']
print foo(a)