There were several proposals still on the project ideas list without a confirmed mentor. At this point if a mentor hasn't come forward it seems very unlikely one will.
Student applications are now open, and it would be really bad to have students apply for these projects when in reality we can't accept them. Therefore (and with support from people on IRC) I've moved those projects to the existing "ideas without a confirmed mentor" list, and added a warning not to apply for ideas on that list. This is the current contents of that second list - if you're a student and thinking of applying for any of the following projects, then sorry but you should probably pick a different project. Without a mentor they simply can't go ahead: https://wiki.debian.org/SummerOfCode2018/ProjectProposals/BroadcastDataFromGPredictForOtherHamRadioApplications https://wiki.debian.org/SummerOfCode2018/ProjectProposals/CleanRoomForPGPKeyManagement https://wiki.debian.org/SummerOfCode2018/ProjectProposals/ClickToDialPopupWindowForLinuxDesktop https://wiki.debian.org/SummerOfCode2018/ProjectProposals/CreateASuccessorToTelifyUsingWebExtensions https://wiki.debian.org/SummerOfCode2018/ProjectProposals/FirefoxAndThunderbirdPluginsFreeSoftwareHabits https://wiki.debian.org/SummerOfCode2018/ProjectProposals/KanbanBoardForDebianBugTrackerAndCalDAVServers https://wiki.debian.org/SummerOfCode2018/ProjectProposals/Port%20Kali%20Packages%20to%20pkg-security https://wiki.debian.org/SummerOfCode2018/ProjectProposals/SocialEventAndConferenceCalendars Cheers, Olly