Once upon a time Microsoft's service packs for Windows were something to wait for. The company tended to use service packs as a way to introduce support for new technologies that had gained traction in the market since an operating system's launch.
Windows 95 OSR2 brought in the first support for USB, Windows XP SP2 revamped wireless networking support, Windows Firewall and Data Execution Prevention. Windows Vista service packs brought everything from performance improvements to support for new technology like EFI and even a retrofitted chunk of Windows 7 features.
This is in stark contrast to the first Service Pack for Windows 7. It contains quite minor feature updates including a revamped remote Desktop client. However the main purpose of the Service pack is to collate all the updates that have been released since the OS was released to manufacturing on July 22nd last year.
Windows 7 Service Pack 1 has now entered beta, and while there is currently no schedule for an official launch, it can be downloaded and installed by going this Microsoft TechNet page.
Despite the lack of features this is going to be a boon to anyone who has suffered through the near endless cycle of downloads, installs and reboots that comes after a Windows 7 install. To give an idea of how much data is sucked down after a fresh Windows 7 install the Service Pack weighs in at 1.2GB. By rolling all those patches into the one package you can save having to suck down that much data every time you reinstall Windows.
If your Windows 7 system is up to date with patches then there isn't really any need to rush out and grab the Service Pack. However for those about to do a fresh install using the Service Pack should be preferable than entering into the seemingly endless loops of update downloads and reboots.