After this weekend's upgrade my primary account can no longer access the Community.
Secondary accounts -- like the one I'm posting from now, which is on the same Marketo instance as my primary -- appear fine.
When my primary account accesses the same URL https://app-sj01.marketo.com/guide/displaySuccessContent?contentTag=main_MarketoCommunityHome:
Note the account is still getting email notifications, it just has no web access.
Anybody else seeing this?