Well! Back when this blog started, I made a promise not to upgrade until it was totally safe, and now I think it is. 2.6 was not actually dangerous at any time, but I have gotten good results from testing it in the current release on my Mac and my PC in version 2.6.6, so my suggestion to you is to go ahead and grab it as soon as possible. Still Free, so that's brilliant.
Some of the tools have been upgraded. I like what they've done with the lasso tool in particular.
All the old posts on this blog now bear the tag "GiMP 2.4/2.5", and all future posts will bear the tag "GiMP 2.6" until such a time that the upgraded version moves on sufficiently to note it.
And since this isn't much of a post, I'll open the comments for any suggestions or questions. I know one outstanding tutorial suggestion is how to make your photo into a pseudo-cartoon like my avatar is. If you have other suggestions, here's a good time to post them for my review.