So my spouse and I went to our local CIS office for infopass yesterday. Fortunately, we had a friendly and helpful, albeit a bit business-like, late mid age (50s-ish?) gentleman. He called the database for the information and printed it out for us as he explained the case status to us, and all the spouse's information was right in place, and there was no problem in that regard. Which was good.
A couple of interesting things.
As my sig shows, my own case got approved in about four months. However, he showed my security check (inc. namecheck, which was initiated soon after they received my application) was cleared in less than a month. Which might mean they just sat on my case for some time (one caveat: I had some applications with Nebraska in the past [F-1, H1-b], and I have no idea how long it took before they merged my T and A files). Further, the spouses current status was "pre-adjudicated" but her security check was all cleared in a month too. So, there is no real issue that has to keep her case from getting approved at this point. The officer explained that her case is just sitting there just waiting to get approved.
The officer said the CIS does not approve cases as the results of security check come back in. He suggested there is a 30-90 days cycle of adjudication for the CIS's "structural reason"; some ready-for-approval cases may serve as sorta pressure valve so the CIS calibrates the number of approvals (which kinda makes sense to me if it's true -- I'd guess they certainly do not want to use too many visa numbers at a time early in the fiscal year, or too few visa numbers at the end of the fiscal year).
Some forum people here said to me privately that the CIS might just waiting for her case to hit the official processing time, at which point they would approve it hopefully. After the infopass, it sounds like that may really be the case (and I somehow imagine it might be easier for the CIS to do so if an applicant's dependent on whatever primary non-immigrant status like H1-b so his/her status is independent of the primary's AOS; my spouse is on H1-b).
At any rate, take it for whatever it may be worth. In fact, the only thing we can be 100% sure of now is all her application information is correctly entered in the CIS database. As for everything else, we'll just see if her case will really get approved around the processing time.