It looks like Microsoft will release a second service pack for Windows Vista before Windows 7 RTM. You can expect SP2 to be very similar in nature to SP1, few or no new features, primarily bug fixes and performance optimizations.
It's confusing because Windows XP Service Pack 2 was such a tremendous change and introduced many new features. You almost expect a second service pack to include more than just bug fixes. In actual fact, XP SP2 included code from the original Longhorn source, so it was practically a major release. Microsoft could have slapped the Energy Blue Theme on the desktop and shipped it as Windows XP2.
However, things have changed within the Windows group at Microsoft. The team is using a revised software development lifecycle with a goal of releasing a new version of both client and server every 2 years. It's certainly working with the group on schedule for Windows 7, so get used to the idea of smaller service packs.
A final word on Internet Explorer 8 - install beta 2 and start using it now. I'm not saying that IT should roll it out with WSUS but it's great for use at home and even the office. Click the screen-shot below and try it out.