According to Winbeta.org, there's a fair chance that Windows XP SP2 will be build 2181, although 2178 and 2180 have gotten pretty close.
The latest release schedule looks something like this:
August 4th RTM and RTAU (Auto Update)
August 9th Release to MSDN and Download Centre
August 24th Release to Windows Update (and SUS) with August 5th bieng the date people can download the full package.
The new service pack includes many, many fixes for Windows XP, as well as a new firewall, memory protection enhancements and safer browsing and e-mail.
Would you like to know more?