My Exchange 2007 build number doesnt update with Rollup X...

How do I know if my application of RU has worked?

Why hasnt my build number updated in EMC/EMS/AD/anywhere?

So many questions...

As with previous versions of Exchange the build number in the consoles/AD etc is only updated on a Service Pack, and not on an interim rollup. This saves any confusion regarding why certain build numbers dont equate exactly to the rollup number.

So the next question is how do I tell the build number then/how do I know if it worked?

Add/Remove Programs will show the presence of the interim rollups for Exchange 2007. The other essential check is the setup logs, please do take a look over these after an update install. If nothing else scroll to the bottom of the file to ensure it all looks clean. This is your best bet on ensuring the install went well, that and there were no errors on install!