If you mean unique items it is a shade over 1,000,000 with most other things limited by available memory (the size of which (the pool) is also greater in 2007.
Report filters and value fields in P/T Reports and Charts are limted to 256.
Finally length of names for MDX names for an item and relational strings are just over 32,000
Regards
Nick Hodge
Microsoft MVP, Excel
Southampton, UK