[UPDATE (08.30.2012): The Bx1/Bx2 service reductions effective July 1, 2012 weren't a "stealthy service cut;" it turns out that MTA typically reduces some service systemwide during the summer due to lower-than-average ridership during summer months. Regular service resumes in September.]
A few months ago, MTA released a report detailing proposed changes to bus service for the summer (specifically p. 111-114 of the document). Schedules for 21 routes would see adjustment, but a look at current MTA bus schedules shows adjustments to several other routes – including more cuts to the Bx1 and Bx2 in what looks like a seasonal adjustment.