Here's a change in progress: the well-established adjective lexeme ready has for some time been slowly turning into a verb. Webster's only gives it as a transitive verb (as in They were readying the plane for departure), and even in that use it's relatively new: texts from early in the 20th century contain absolutely no forms like readying, readies, or readied. More recently there is something newer — new enough that I don't recall noticing it before: the other morning I heard an NPR announcer talk about a Boston sports team (don't ask; I don't do sports reporting) that was "readying for" a game against some other team (Miami?). That's an intransitive use of the verb. Intransitive uses are in fact attested from the 1980s: a scan of the 44 million words of the useful (and inexpensive!) 1987-89 Wall Street Journal corpus comes up with four occurrences of readying for (I exhibit all four of them at the end of the post below). But readies for does not occur at all, and the six occurrences of readied for are all passives (so they illustrate the transitive verb).
This intransitive verb is new. It has hardly been born, in linguistic terms (where changes normally come only as generation follows generation). It is not just an ordinary verb meaning "get ready". Imagine this: your partner is waiting for you to finish dressing and preening so the two of you go out, and shouts up the stairs, "Come on! We need to get going!". I don't think you can call back, "Just a minute; I'm readying!"
It seems to me that the way things are right now, you can ready something for use, as most large modern dictionaries acknowledge; and to a very limited extent you can ready for something (a use that most dictionaries do not seem to have caught up with yet). But that's just about it, I think. It's obligatory to have either a direct object or a preposition phrase with for. The unfolding verb ready has a few more decades of slow spreading before it is more fully available for intransitive use (if it ever is; it is quite possible that it will never happen).
The situation might be compared with a similar case, the slow spread of grow as a transitive verb. It seems to me that a few decades ago the only transitive use of this verb was in agricultural and biological contexts: you could grow carrots or geraniums (there the verb meant "cultivate"), and a lizard could grow a new tail (there it meant "come to have as a part of the body through a biological process"), and that was about it. You couldn't describe blowing up a balloon as "growing a balloon", even though by inflating it you were causing it to grow in size. But at some point a new use began to emerge: businessmen started talking about "growing a business" (there are 19 occurrences in 1987-89 Wall Street Journal articles). And then in the presidential campaign of 1991 one of the candidates, William Jefferson Clinton, starting talking about how we had to "grow the economy". The press picked it up, and soon there was a new possible object of the verb. I imagine it may now slowly spread out through the economic realm picking up other suitable direct objects as the sense "cause to become bigger by means of economic management" becomes entrenched. (Added later: Dirk Scheuring points out to me that by 1998 Guy Steele — the author of the SCHEME programming language) had written a paper called "Growing a language".)
So as ready slowly increases its reach as an intransitive, grow is slowly increasing its reach as a transitive. Though let me stress that what I have offered here is not an expert opinion; I have done no serious quantitative work on this topic, and I have no real expertise in diachronic lexical semantics. I have no doubt that the blogosphere will be able either to correct me or to extend what I've said.
Here are the four late-1980s examples of intransitive readying for as promised:
If enough chief financial officers expect the window to slam shut shortly, the pipeline (where deals are readying for market) may get clogged.
And out on Long Island Sound, a number of dinghies from the Larchmont Yacht Club jockey for position, readying for another afternoon of racing.
Against this uncertain background, Europe's steelmakers are readying for 1992.
The Navy had been readying for a grapefruit-sized satellite called Vanguard, and this was rushed to Florida for a quick blast-off in December 1957.
P.S., next morning: And the blogosphere has already come through. Eliah Hecht at Reed College went all the way through the Oxford English Dictionary entry (I was working last night without access to the OED), and found intransitive occurrences from as early as the late 60s, and one of them introduces something really new: verbal ready, in the present tense (from a photo caption, I think), with an infinitival complement clause!
Posted by Geoffrey K. Pullum at November 15, 2005 10:20 PMb. intr. or absol. To make oneself ready or prepare in any way. U.S. 1967 Wall St. Jrnl. 12 Dec. 1 Machinists Union President Roy Siemiller, readying for aerospace bargaining, and Steelworkers chief I. W. Abel feel they must match the big rubber and auto settlements. 1972 Time 17 Apr. 22 (caption) In a cloud of catapult steam, a U.S. jet readies to attack Viet Nam.