Source: NEXUS SC: The System Center Team Blog
Paul Ross announced that Service Manager will now not be released until the first half of 2010, with a beta refresh available towards the end of 2008.
Mean reasons of this delay are the requirements that came as feedback from the first beta. The feedback was summarized as:
To meet these requirements they decided to replace specific components of the Service Manager infrastructure.
For more info on the delay go to weblog and read the FAQ that explains the main points regarding the delay.