http://cid-ec92aae47a89073b.skydrive.live.com/browse.aspx/Emulation/Dolphin usually has the newest builds.
4302 is currently available, and that's the newest on Google Code.
I just posted this message on this other thread about Skies of Arcadia, but i guess it would be nice to post it here for those who didn't see. It showcases more of the "Widescreen Hack" in dolphin:
http://www.neogaf.com/forum/showpost.php?p=17663688&postcount=71
There isn't much to elaborate.
It widens the field of view and the amount of information on screen. Only 2D elements (HUD, menus, text) get stretched, because there's no real way to not stretch those. 3D elements stay in perfect ratio.
However, you must remember that these added areas to the left and right were never meant to be seen, so there could be some geometry popping and texture loading in these areas (as, since they're not visible in the original game, programmers can clean them to save resources).
In these pics, you can see that the aspect ratio is correct, but there's more image information on each side:
You can see more of her ship in this example (not exactly the same frame, but the actual scene doesn't change that much. Every other screenshot is the same screen tho):


You can see the rest of the ship's bridge, to the left and right:


Extra cannons on the background, you can also see more of the soldier's bodies


You can see the rest of the ships in the background:


Again, more on the surrounding areas and background (the green "thing" on the left of the image, which you can see MUCH MORE in the widescreen version, is actually Ayla's weapon).


Emulation is not quite there yet, tho. Sound is all weird (missing samples, music loops, only plays on one channel), and sometimes there's a graphical glitch here and there (red shadows, mostly in this begging area). Overall speed is also not quite playable (aka, it's too slow on my overclocked qx6700 running at 3.2ghz and 8800gtx).
It's getting better with every SVN release tho, so here's hoping.
PS.: I used la.gg because they create automatic thumbnails. So, advanced sorry for when these pictures disappear in the coming months, I guess?