I experienced the exact same situation.
Assuming the users are not changing the time zone in GW Web options, I corrected our issue via ConsoleOne, onnect to the Primary Domain.
Check the DST settings by Tools -> GW System Operations-> Time Zones
The start and end dates for DST were set to the previous start/end dates. I changed them for each time zone we have offices in to the 2nd Sunday March start, 1st Sunday November end, restarted the gW agents and GW Web reflects the correct time.
Hope this helps