UPDATE: In a press release issued Tuesday, Apple announced that customers who pre-ordered 3G iPads will receive them on April 30, and that units will be made available for sale at Apple retail stores at 5 p.m. local time. The company seems to have delivered on its “end of April” promise after all, with 7 hours to spare.

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According to Apple’s (AAPL) Jan. 27 press release, the iPad 3G was supposed to be “available in April in the US and selected countries.”

By March 5, when Apple announced that the iPad Wi-Fi’s original March ship date had slipped to April 3, the 3G model’s “available in April” had become “late April.”

Last Wednesday, when Apple let it be known that international iPad sales had been pushed back to May, it mentioned in an aside that the company had “also taken a large number of pre-orders for iPad 3G models for delivery by the end of April” — wording that, in retrospect, left open the possibility that delivery might not actually happen by then.

[UPDATE: As several readers have pointed out, Apple cleared up that ambiguity Monday morning with a mailing to early pre-order customers to assure them that their 3G orders would be shipped in late April “as communicated at the time you placed your order.”]

Steve Jobs — who can be a master of misdirection — was even vaguer. When a customer asked “will the iPad 3G models still ship on time as planned (end of April) in the US, if I order one today? Or will the 3G US orders be postponed as well?” Jobs’ one-word answer, e-mailed from his iPhone, was a terse but ambiguous “Yes.”

Early Monday morning, we found out that both meanings were operative. According to Apple’s letter to customers, early pre-orders will ship on time. If you order an iPad 3G today, however, shipment will be postponed until as late as May 7th.

Apple attributes all this to “surprisingly strong” demand for the new device. But by definition it’s also having trouble building them fast enough.

NOTE: An earlier version of this article, written before Apple’s letter to customers came to light, had a snippier headline. It’s now clear that it was out of line.

[Follow Philip Elmer-DeWitt on Twitter @philiped]