To Get the SharePoint Versions:Go to any document library you will find it at the top
And here you are the version number of the deployed components:
MOSS 2007 or WSS 3.0 June 2009 Cumulative update: 12.0.0.6510
MOSS 2007 or WSS 3.0 April 2009 Cumulative update: 12.0.0.6504
MOSS 2007 or WSS 3.0 Service Pack 2: 12.0.0.6421
MOSS 2007 or WSS 3.0 Feb 2009 Cumulative update: 12.0.0.6341
MOSS 2007 or WSS 3.0 Aug 2008 Cumulative update: 12.0.0.6327
MOSS 2007 or WSS 3.0 Infrastructure Update: 12.0.0.6318
MOSS 2007 or WSS 3.0 post-SP1 hotfix: 12.0.0.6303
MOSS 2007 or WSS 3.0 post-SP1 hotfix: 12.0.0.6301
MOSS 2007 or WSS 3.0 post-SP1 hotfix: 12.0.0.6300
MOSS 2007 or WSS 3.0 SP1: 12.0.0.6219
MOSS 2007 or WSS 3.0 October public update: 12.0.0.6039
MOSS 2007 or WSS 3.0 August 24, 2007 hotfix package: 12.0.0.6036
MOSS 2007 or WSS 3.0 RTM: 12.0.0.4518