For any MVers interested in the difficulty of an ascent of the In Pinn itself...
First up, it's a magnitude of difficulty harder than any mainland Irish summit, and it's sensible to have rock climbing experience in the party. The easiest way up is the stepped East Ridge (the far side in jackill's excellent pic). This gets a rock climbing grade of Moderate, and could conceivably be done unroped by the very (very) experienced scrambler in good conditions (disclaimer; that's just my opinion!), but they would have to contend with a borderline unjustifiable degree of exposure (the ridge is in places about six inches wide, and has (to quote one Victorian pioneer) 'a bottomless drop on one side, and an even bigger one on the other'). The vast majority will proceed roped.
Because of the huge pendulum potential of a roped fall from the East Ridge, many folk prefer to do the West Ridge instead (the apparently vertical stepped wall facing jackill's camera). This is definitely rock climbing rather than scrambling (although given the lowly grade of Difficult...that said, one leading local guide told me that polish and hold loss probably meant it was Very Difficult these days). The holds are generally good and positive throughout the route; depending on your height the crux will be either the move between two slabs just over halfway up (obvious in the photo, and very easy for those of us who are 6'3 who can reach the good holds and thus don't have to mantleshelf it), or pulling around the shard of rock visible on the left edge of the In Pinn just below those slabs in the pic (when you're tall you are a bit bunched up doing this move, and it's thus quite strenuous).
Descent is by abseil; there's a chain in place (or at least there was!) under the capping Bolster Stone (the bit with the bird perched on it) on the summit. It should be noted that thanks to a lightning strike mangling the previous highpoint, the true summit of the Pinnacle is now the top of the Bolster Stone itself, which adds a stinger of a move to all the other fun and games you need to go through to make an ascent.
If you're not a climber but are brave, enquire locally (or online) about a guided ascent. You'll need about half an hour's worth of courage, and you'll get a lifetime of memories from it. Linkback: mountainviews.ie/summit/B1240/comment/15233/