At least on Win7 x64 with the 0.4.0-beta, I'm seeing in excess of 60^H^H70 simultaneous connections to/from the client.
This seems excessively high, for one. Additionally, there is no mechanism in the client itself to change the number, short of creating a bitcoin.conf (I limit my services wallets to 16 connections, already IMHO more than enough).
That is more a result of the bitcoin network not working well, it needs some serious examination, but so far (AFAIK) no one has stepped up to figure out why there are so many connections to any listening node.
There is a limit - currently 100 IIRC, though I would vote for the option to change that in the GUI options menu.
Setting it lower is something that would have to be thoroughly discussed first. As I mentioned, the network is already starved of nodes which accept incoming connections, limiting that number further could have very serious consequences. Someone needs to do some analysis of the network, but until then, the max connection limit really shouldnt be touched IMO.