Yes... that is what Microsoft reports:  4GB data.

Here's an excerpt from the MSDN site:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnsse/html/sseoverview.asp

The SQL engine supports 1 CPU, 1 GB RAM, and a 4 GB database size. ... The 4 GB database size limit applies only to data files and not to log files. However, there are no limits to the number of databases that can be attached to the server.