What about (if the strings are the same length):
s1='abc'
s2='xyz'
s3=''
for x in range(len(s1)):
s3 += '%s%s'%(s1[x],s2[x])
I'd also like to note that THIS article is now the #1 Google search result for "python interleave strings," which given the above comments I find ironic :-)
