Ok here's the skinny with PSN+. It is a subscription server side that ties in to your account. The subscription icon itself is not shareable but once your account is subscribed you get
1.certain games for free, These games are all shareable on up to 5 PS3's until the subscription expires, as long as you maintain the sub, you all keep the games.
2.good deals on other games, Since these games are purchased, albeit with a discount, you and all 5 PS3's get to keep them indefinitely.
and
3.a few service perks. One of the perks is Auto update of your recently played games. This is where things get complicated. Since they are account level services they only work on the subscribed account, and so far they only work on 1 PS3 at a time. For example. I have a main account, and I'm a member of a long term PSN group where we opened a seperate account where we buy games and share them. I activated Auto Update on that account on my PS3. It made me set that account up to auto log in when my PS3 turns on so now instead of auto logging in to my main account like I used to, now everytime I turn on my PS3 it auto logs in to the share account. Not a big deal, it auto updates all my games for me. Other snag is it only checks for games launched on that account so I had to go through all my games again and launch them under this account name so it would check them at the designated time. Kinda of a big deal. Now here's the major kicker. When my other gameshare buddies tried to activate this on their PS3's they got a message saying they couldn't, that it was already in use by another PS3. So we've began discussion on how and when to take turns. Since it is a daily check and such a hassle to set up my suggestion was we each rotate a month on this service. Who knows, no details have been hammered out but I would go into sharing PSN+ assuming that you won't get to take advantage of perks like this. I guess if your doing a one time group the Leader could keep these perks and pay a little more than the rest of the groups since he's essentially getting the hook up.
This is my experience with PSN+ so hopefully this "is PSN+ shareable?" can be squashed. the answer is, yes, PSN+ is almost completely shareable. (also the Hulu+ app I got through the PSN+ early promotion (it will eventually be available to all PSN users) worked just like any other game on my main user account)