I don't use gmail myself, but for the last 3-4 weeks have heard widespread complaints about slowdowns, inability to login, and intermittent blocking. Also some people reporting problems with google search, googlechat (or whatever it's called) and some other functions.

There have also been some reports of certain VPN's (mostly the PPTP type) becoming unuseable or of limited operability during this period. Speculation is that the Net Nannies are tinkering with new filters or enhancements to the GFW.