The futon critic is a reliable source for episode titles, numbers, and airdates. It shows that Phil's Sexy, Sexy House is episode 708, but it airs before episode 707, Clean Out Your Junk Drawer. The episode number of Phil's Sexy, Sexy House is supported by ABC's official press site . You're right to cite Wikipedia as an unreliable source. The info there was probably added by someone who only took into account the air dates.
Contrary to the episode order as decided on by the writers (and thereby, the correct one), the order of broadcast is actually decided by ABC. I'm assuming that because of the hiatus between 706 and what was supposed to be 707, they didn't have enough time to air all the episode before winter hiatus, given that they have two thematic episode (708 for Thanksgiving and 711 for Christmas) that need to be aired before said hiatus. So, they needed to get 708 out before Thanksgiving, making this Wednesday the only available spot as they never show new episodes the week of Thanksgiving itself, and thereby switched 708 and 707. Same goes with 711, that has to air before the hiatus, thus pushing back 709 and 710.