If you have not gotten word by other means, SMS 2003 SP3 has shipped and is available on the web for download here!
There has however been some confusion over the SMS 2003 R2 product in conjunction with the SP3 release which I hope is cleared up by the following.
SMS 2003 R2 remains a distinct value-add for SMS 2003 and requires either SMS 2003 SP2, or SMS 2003 SP3 versioned sites. R2 provides added functionality including both the Scan Tool for Vulnerability Assessments and the Inventory Tool for Custom Updates. Find more information about the SMS 2003 R2 evaluation version here!
SMS 2003 SP3 does not require R2 nor will it provide, impact, or duplicate the R2 functionality. SP3 does introduce RTM Vista Support and Asset Intelligence features to SMS 2003.
Some original wording on the SP3 download site looks to have been changed which should eliminate future confusion around SMS 2003 SP3 and R2.