A small security update for OS X Snow Leopard and Lion users is now available from Apple, addressing an issue regarding fraudulent certificates from DigiNotar, a Dutch certificate authority organization. The security issue arose when DigiNotar’s servers became compromised by hackers a few weeks ago, who managed to obtain access to 531 of the company’s certificates without their knowledge until weeks after the intrusion took place. Although Apple has taken a while to respond to this issue, they’ve finally revoked DigiNotar’s status as a trusted source with Security Update 2011-005.

In some respects, it already has. In his WWDC keynote yesterday, Steve Jobs pointedly reiterated his declaration made at the iPad 2 announcement last winter that we’ve entered the “Post PC” era. The Mac OS X 10.7 Lion upgrade will only be available as an online download, and not on hard media, which is a major departure from Mac OS tradition.

Oh my. The Mac community is abuzz with yet another rumor of a forthcoming Apple Tablet—which is odd. Steve Jobs has publicly spoken about netbooks, declaring, “We don’t know how to build a sub-$500 computer that is not a piece of junk and our DNA will not allow us to ship that.” The iPhone and iPod Touch are already good handheld computers…it is tough to see where a larger tablet-format screen would add any value.

Assuming you had the right hardware, properly loaded software drivers, and the gods of fortune were smiling favorably upon you, Windows Vista brought what was arguably one of the biggest changes to the Windows User Interface since Windows 95. XP really warmed over what had already been accomplished, then wrapped it in some plasticy looking windows. By contrast, all versions of Mac OS X have delivered serious updates to the user interface, though we will have to wait to see what, if anything, Snow Leopard presents us.

It seems the MacBook refresh may have brought a new feature to OS X in the form of GPU accelerated h.264 video decoding. Currently, improvements to CPU load can be seen with new MacBooks, but the feature could find its way on to a Mac with appropriate hardware near you.

Some MacRumors forum members have been talking about how the new MacBooks handle HD video content.