Here's some exciting news for you bibliophiles and textual critics out there: the 28th edition of Nestle-Aland is scheduled for publication later this year or early next. Nestle-Aland is the standard, scholarly edition of the Greek New Testament.
I don't know that the 28th edition will represent a significant change over the 27th in terms of information in the apparatus criticus (the Greek text itself hasn't changed since the 26th). Apparently the apparatus will be made more "user-friendly", but I've seen no indications that it will include a greater variety of witnesses. Indeed, the apparatus in the 27th edition was not significantly fuller than that in the 26th. The 28th edition will come with a CD-ROM, however, and that should facilitate things very nicely.
I will probably get the 28th edition. I always get the new edition. It's getting kind of expensive, as the new editions appear with rather alarming frequency these days, and I have this rather unhealthy passion for leather-bound editions, which aren't cheap. I tell myself it's worth it, and I always make it a point to actually use them (I read the New Testament in Greek from cover to cover every Lent as a kind of devotional practice), unlike some of my books.
I hope the CD-ROM has nice pictures on it.