I've been doing this since 2003 and haven't missed a season yet (even if I'm late here and there). If you poke around elsewhere on the net (and if you care) you might find previous mixes, but I'm going to start posting them here from now on because why not, I have a blog so why not use the damn thing.
The Summer 2009 mix is called "Chameleonic Tendencies" and it goes like this:
1. Passion Pit - Moth's Wings
2. Department of Eagles - No One Does It Like You
3. Yacht - Psychic City
4. Atlas Sound ft. Noah Lennox - Walkabout
5. Animal Collective - For Reverend Green
6. Volcano Choir - Island, IS
7. Dirty Projectors - Useful Chamber
8. Mew - Vaccine
9. Phoenix - Armistice
10. Miike Snow - Sans Soleil
11. Yeasayer - Tightrope
12. Nine Inch Nails - Discipline
13. Grizzly Bear - About Face
14. White Denim - Regina Holding Hands
15. Los Campesinos! - We Are Beautiful, We Are Doomed
16. Sufjan Stevens - You Are the Blood
(BONUS QUESTION: I never have more than one song from an artist on a single mix, but I kind of cheated twice - you might even say three times - on this one. Can you find them?)