If for some reason, Intellisense does not work for you when using SQL Server Management Studio 2008, then check for the following:
1. Go to Tools > Options > Text Editor > Transact-SQL > Intellisense and make sure the Enable Intellisense checkbox is checked
Also go to Query > Intellisense Enabled to verify that Intellisense is Enabled.
2. If you are not able to see intellisense only for the latest schema changes , then you need to make sure you refresh the cache. The intellisense relies on a local cache which you need to manually refresh.
There are two ways to refresh the cache:
a. Go to Edit -> IntelliSense -> Refresh Local Cache and
b. Hit Ctrl+Shift+R
Once you have performed these steps, open a new query window and you should get Intellisense back on your SSMS 2008
Note: If you are using SSMS 2008 to connect to SQL Server 2000 databases on the network, then intellisense does not work for down version systems. Intellisense only works when you are connected to a 2008 server instance.