Paul wrote about it first (as far as I know) as he is at Tech-Ed this year and posting stuff as it happens.  One of the things that Exchange 2003 SP2 will do is increase the database size limit from 16GB to 75GB.  The limit on the number of Storage Groups still applies, but this should help out the smaller businesses using Exchange as well as the remote sites.  There are some other features that are included in SP2 that I am waiting to be publicly announced before I can talk about it.  This was one that surprised a lot of people.  Good.