I didn't think this was possible. Mac owners, particularly dual-booters, may have run into trouble accessing Windows-formatted external hard drives or partitions. I certainly did. In swept Google out of nowhere with MacFuse, a "mechanism" (their word, no doubt for lack of a better one) which allows people to implement their own file systems for OSX. Naturally. I can envision Andrew writing his own file system, but I suspect the rest of us will want to grab NTFS-3G, which is an implementation of NTFS. (Download is at the bottom of sketchy blog post.) I was skeptical, but it worked great. Install MacFuse, install ntfs-3g, and suddenly OSX can read and write to my Windows partition.