Thanks once more, I see I have satisfactorily confused everyone! Putting into practice the Buddha’s strategy of making some enigmatic remarks and then disappearing. 
Many of your remarks were very kind, and you’ve rightly pointed out many of the features I was aiming at in the translation. But let’s have a slightly closer look at the verses.
Now, as a bit of background, Pali verse is typically organized in terms of four-line stanzas. This is an extremely common form. So much so, in fact, that it sometimes gets imposed as a default in cases where it is not strictly warranted.
Consider how recitation is done. When you’re chanting verses, you don’t necessarily indicate the end of a four-line section. Maybe you’ll pause or emphasize it, but it is not really definitive. In some cases, of course, the break point is clear, for example some verses will contain a “refrain” in the final line that definitely indicates the end of the verse. But in many cases it’s somewhat arbitrary. And while the four-line stanza is the most common unit, we also fairly commonly find verse copied or repeated in different places as a group of two, or even one line. So the “unity” of the four-line stanza is fluid, and may be imposed inappropriately.
Now, to return to our verses, if you check Ven Bodhi’s translation, you’ll see that he, like most translators, implicitly accept the division into sets of four-line stanzas. In addition, check out his notes on these verses. The nature of the text is such that it attracted a deal of attention from the commentaries, which read them according to their own ideas, not all of which are justifiable. Ven Bodhi rightly rejects some of their readings, but I am not sure he goes far enough.
If you look at the first two verses, I’ve divided the first couple of lines off. Now, see the way these lines, with their invocation of “past” and “future”, echo the next couple of lines? This lends a unity to these lines, and gives the impression that they belong together. But here’s the catch: such similarities can just as easily be a reason for stitching lines together. That is to say, the similarity might be a sign of them belonging together, or it might be a cause for them belonging together. Tricky, right?
But check line number five:
Paccuppannañca yo dhammaṃ
The key here, I think, is the little ca. This means “and”, and it is an enclitic, i.e. it is usually used after each item in a list (like a comma). Now, this is not completely consistent, especially in verse, where the constraints of meter often dictate that a ca will be lost. I’m not aware, however, of cases where a ca is superfluously added just to make up the meter: there are other particles for that.
So the ca co-ordinates with other items in a list, and here that is defined in the previous line:
appattañca anāgataṃ
This suggests that these two items, and by inference the previous line, form a unit. The first two and last two lines are less strongly connected. This might be a sign that they were added later, but I wouldn’t think so. More likely, it seems to me, is that the verses were simply construed in this way. There’s no reason to think that the Buddha was incapable of playing with literary forms! So regardless of whether we think these lines in literary historical terms belong in the same stanza, they clearly form a semantic unit, which is why I translate them together.
This doesn’t necessarily change the reading of the text, but it does shift it slightly. In my reading, the line “having known this, foster it” clearly applies to the whole of the preceding verse. That is, the process of insight involves understanding, by inference, the present in its context. Past, future, and present are all, by either inference or direct observation, part of the scope of insight.
However, if we take this line to belong only with the “present” couplet, it appears that “having known this, foster it” applies only to observation of present phenomena. Or at least, that’s how I understood the translation before going into the Pali. This suggests that giving up past and future is merely a precursor, and that the fostering of insight is solely grounded on observation of present phenomena.
While this is not definitive, it does agree with the long-term trend in the Theravadin abhidhamma tradition, which strongly emphasized the reality of the present moment. This emphasis, of course, when applied to meditation led directly to the modern vipassana movement.
So there you go, that’s why I divided the verses up like this, and how it relates to the development of Theravada doctrine and meditation!