Update: This has been fixed but the actual numbers and profile pictures might not look right until tomorrow afternoon due to caching.
Recently, some people began noticing a decline in their following and follower numbers. We investigated and determined this was caused by an error during a database upgrade. We’ll be restoring followers throughout the day to those who were affected and keeping the status blog and Get Satisfaction forum updated with specifics.
Please note that this is unrelated to our ongoing spam initiative as some folks were wondering. Twitter fights spam by putting rules in place to inhibit certain activities. We don’t automatically delete accounts en masse.