Well, it took eight episodes, but O'Neill finally got his Captain Kirk moment. On a trip to the planet Argos, a beautiful woman gives him some space cake and an exotic dance, and takes him to bed. Unfortunately the bodily contact transmits nano-scale machines into O'Neill's blood which then begin aging him rapidly. The team have to figure out a way to stop this before he dies.
The makeup department did a really good job of making Jack look old, and I think had Richard Dean Anderson not gotten really fat lately, he'd have looked quite similar to the way they made him up here.
There's not much character development on this planet-of-the-week - all we see from Jack is the start of a letter to Sara, his ex-wife (a letter he never takes further than 'Dear Sara') and the promise to treasure every day in the rest of his life. The rest of the team barely do anything, it seems. Daniel delivers a baby, him and Teal'c translate some obscure archaic goa'uld (which, it turns out, is what Linear A script is), and Carter does some sciencey stuff with Dr. Frasier. All in all, quite a weak episode, but still an enjoyable one to watch. My favourite part is Alekos realising that, with a lifespan of thousands of days, he could go out and explore the uncharted parts of his world, then return and share his knowledge with others, who could build on that knowledge. It's like watching him discover history and science.