To verify the reported bug, I updated my mobile phone number in my user profile, and ran the two sync timer jobs. This is how my updated user information looks in a team-sites:
And this is how my non-updated user information looks in my personal site:
As you can see from the time stamps in the lower left corner, the profile data is still exactly as cached in the UserInfoList when I first created and visited my personal site. As of now I don't know any fix for this issue.
[UPDATE] A list of things to check, not all applies to SP2010 though: Troubleshooting User Profile Sync issues in Microsoft Office SharePoint Server 2007
As it turns out, all our personal sites get the "ProfileSynchronizationInternalException: ProfSynch: The site with ID <guid> cannot be synchronized due to an unprovisioned root web" error in the ULS. This seems to be a common problem in SharePoint 2010 according to this MSDN forum thread, which also provides an unsupported workaround that updates the Flags column of the Webs table in the My Site Host content database.
