It looks like the ability to read/write to NTFS partitions in Linux has arrived.... again...
Originally, we had captive-ntfs, which was the first real contender that brought read/write support for NTFS. It worked by wrapping the "NTFS.SYS" driver from Windows, and required a valid Windows license to use (legally, that is). Unfortunately, captive-ntfs wasn't compatible with the 2.6 kernel for a very long time. However, earlier this year, a new version was released that does work with the 2.6 kernel (most modern Linux distributions use the 2.6 kernel, making this a pretty important feature).
Unfortunately, captive-ntfs isn't quite the end-all-be-all solution to the NTFS problem. It's not the speediest method ever conceived and it does require a Windows license to legally use. For most people though, neither of these problems are an issue. Lastly, there are reports that the driver is still rough around the edges.
Meanwhile, the Linux-NTFS project has continued their "slowly but surely" approach to the problem, and it appears that the project may just have reached fruition. The ntfs-3g driver provides a decently fast, completely open-source (and Microsoft-free) approach to the NTFS read/write problem. It's also in active development, unlike the former solution.
If you're dying to be able to write to your NTFS partition, check out the announcement (complete with installation instructions. If you're an Ubuntu user, you can snag some slightly different instructions over here.
(Edit: Or if you're into broken english, here's another easier (aside from the engrish) ntfs-3g Ubuntu HOWTO.)
Read/write support is one of those problems that just hasn't gone away over the years, but it seems like many peoples' hard work is finally paying off. It'll be nice to finally be able to read/write to NTFS drives "out of the box" in Linux.