I'm running CM10, and in system settings there is an Advanced tab under /Device. It allows you to set the default storage to external SD. It was rather strange browsing the basement the first time in RE. I opened the ui, hit bookmarks/SDcard and wound up on external_SD. It's frickin' sweet.
/SDcard/Android (data/obb) is now /external_SD/Android (data/obb). I have a few GLU games with like 3Gs of data and I had a heck of a time figuring out the mount points, cuz there's like 50!? I would move an app to sd and it was fine, until I rebooted, ALL GONE. It's kind of a funky setup, lots of the apps use different paths to reach the same destination. However I did notice you can't access /asec or /secure through /storage. In my directory /external_SD=/mnt/external_SD=/storage/external_SD. The same holds true for SDcard. Both are linked to root so I don't know why some apps take the long way home. Need the exercise I guess.
Back in the Froyo days /mnt/asec and /mnt/secure_asec were your SD apps, you knew right where they were, now we got /data/app-private (which is silly, change the perms, move the app, and dump the zip, I don't get it), /data/app-asec, /mnt/asec, /mnt/secure/asec. /data/asec and /mnt/asec have the same apps, different data (as did Froyo, just without the extra directory in /data). They're all still renamed pkg.apk, so they still won't install without renaming them and changing permissions and jumpin through hoops. I guess that's why we batch backup.
Anywhooo, I'm done, I trust you're still awake. On a sidenote I do like /system Dalvik being in /cache. Took me a few boots to realize that's what's happening when it says "Android is updating". And what's with /mnt/.lfs? JPG's?
Sorry, I'm done