I have heard the term "connectors" used for any 2 cards that streatch (can make a str8), but a IMO the better term is "gappers". K9s is a suited 3 gapper and pretty much unplayable from early position. It does have some value OTB or CO as a blind stealing hand as it's not a huge dog if you get called.
Recently it seems as though I've developed a reputation as being somewhat of a nit, but that comes from trying to adopt some of the playing styles of pro's like Chris Furgson and Ben Roberts. Neither of them are particularly high on playing SC's (the real kind, no gaps) from early position. The logic behind this is that SC's are not profitable raising hands and have the most value in multi-way pots. Since in most cases they would have to throw their hands away to an late position raise, they choose not to play them at all.
In addition, limping from EP with SC's gives too much information as to the nature of your hand. A late postion caller will believe (correctly) that he's safe to bet any 2 cards on a flop with a couple of high cards after you check.
So how about from late position like the CO or button? With SC's better than 56s, in a limped pot, go ahead and join the fun. If the pots been raised fold anything worse than JQs. If the pots still open raise 89s or better.
Still, if you track your HH's I think you'll find that even with optimal play, SC's from any position are at best a break even proposition. I still recommend playing them under the right conditions. The few extra hands you play will allow you to get more action when you do have a real hand.