Installed Jetpack on a new site. When I connected it to my WP.com account (which I've done dozens of times in the past), I got a fatal PHP error:
Fatal error: Allowed memory size of 41943040 bytes exhausted (tried to allocate 30720 bytes) in /my-domain.com/wp-admin/includes/template.php on line 262
The error appears on every wp-admin page, making my entire admin area inaccessible an unusable. When I manually disabled the plugin -- by renaming the /jetpack directory via FTP -- the admin area came back just fine.
I've never had a problem with Jetpack before. Anyone ever seen this? Could it be a server setting? The public-facing website continued to function properly all along.