the "layoff and rehire" is a HUGE plus for you!!
So don't hide it. Your company isn't "hiding it" as if it were shameful. Because it isn't shameful. It's honorable, actually.
They're creating continuous employment in order to keep your benefits active and in force. So that you don't have to start over earning less vacation, or wait to be eligible for a 401k, or for FMLA/vision/dental benefits (which either don't or may not kick in until you've been employed for a year).
They laid you off for monetary reasons; they didn't FIRE you. And then they rehired you in 1 of 2 ways:
• Either SO rapidly that you are considered "continuous" (which means you're so good that they couldn't live without you)
• After that sort of deadline but they like you so much that they gave you this perk to be sure to get you on board (which again means you're so good that they couldn't live without you)
(Also, some companies have as a POLICY that if you're rehired within X months, they have to consider you continuous; again, this is an honorable thing for your company to do, and has nothing to do with the mistaken idea that "being laid off by them, or unemployed by them, was shameful.")
So in your next contact say, "I realize I may have been unclear--My resume ways 'until 2012' because I was laid off in April. But I've since been rehired and am considered continuous because it was so short."
I love LazyDaisy's idea that you should use the "updated resume" bit. And do update your resume to indicate the layff and rehire, because that is really important. Then just email it to HR and say, "here's an updated resume that reflects my current employment situation."
The only *risk* to you is that they might think you're disloyal. But given that your company has shown that it is vulnerable to financial layoffs, it's not that odd that you would want to explore other firms--and specifically, you might be really interested in THEIR job, because now that you were looking for work because of the layoff, you are awake to the idea of other possibilities.
It gives you big negotiating strength as well--you *can* be lured away, but it had better be worth it, since you have the advantage of being so very well regarded by your current employer.