Apple has just pushed a new version of iOS, 4.3.4 (4.2.9 for the Verizon iPhone), and it looks to have "fixed" the PDF exploit
that has been so notoriously exploited of late. In a summary of what's changed, Apple indicates that a fix has been applied that will prevent "arbitrary code execution" when viewing a "maliciously crafted PDF" -- business speak for "we broke your jailbreak, son." And, sure enough, you can see what happens after the break when trying to apply the latest. At this point we're not seeing any other updates or improvements but, really, now that you can view those malicious PDFs without fear on your iPhone or iPad 2, what more do you need?
[Thanks to everyone who sent this in]