Multiple tables vs big fat table

[Mark]

Is it better to have many smaller tables are one larger table? For 
example if we wanted to store user action logs we could do either of the 
following:

Multiple tables:
 - SearchLog
 - PageViewLog
 - LoginLog
or

One table:
  - ActionLog where the key could be a concatenation of the action type 
ie (search, pageview, login)

Any ideas? Are there any performance considerations on having multiple 
smaller tables?

Thanks