After the latest update chunks do not appear at all in SMP. When I connect to a server I get about 3-5 chunks, then maybe one chunk per 10 minutes. My chat lags by about 60 seconds. This is happening on multiple computers across multiple ISP's to multiple servers.
I believe the update has made it impossible to play on servers once your ping exceeds a certain limit. I am from AUS and the servers are usually USA with 300mS pings. I never used to have any problems.