You won't have time to acclimatise, but I wouldn't worry about it - just be prepared to find it harder work than usual.
Oh, and another tip - drink only bottled drinks and don't have ice, even in the big hotels. One of our group was felled by the ice in his G&T - the rest of us who had stuck to the local beer were fine .
Is that the 10k in Addis Ababa? I haven't done the race, but I have run in Ethiopia. Fantastic place. Addis is a madhouse but well worth a look around. The food is great (especially if you like spicy) although injera, the local pancake-type type things that are served at every meal, are a little like bath mats. Watch out for the altitude - it's noticeable even in Addis, and will affect your race time. If you get a chance, try to go for a run on the trails around Entoto, outside Addis. At 10,000 feet you'll really be gasping for breath, but it's where the elites train and if you're lucky you might see a few of them out there.
Sorry to be a pain in the arse about this but Tim, I'd contact the organisers. If the DOB on your passport doesn't march your convocation there might be an issue. You'll probably be fine, but personally I wouldn't take the chance.
Yes, what Dannirr said. We jogged around the parkrun the day before Comrades, my thinking being that I needed to stretch my legs and reassure myself that everything was working after a lot of travelling and sitting about, and also 5k on top of another 89 was probably not going to make a great deal of difference. I'm not sure I'd do it the day before a hard marathon effort though.
Interesting perspective on the med certs this morning from a guy I was talking to who puts on races in France. He always makes sure they're checked properly, because if something goes wrong and the processes haven't been followed, under French law, he's going to jail.
Meadower - good job at the parkrun. Are you likely to be there next week? I was thinking of putting in an appearance.