>That is interesting. Wasn't Jinnah's family Thaker?
Yes, that is true. Not official, nor confirmed, but it is like you noticed, Jinnah was a Lohana (that is my caste / community) so he may have used the std. surname Thaker. It is said that they had some community problems and (not him but probably his dad) converted to Islam. In fact Jinnah (Jina, can't write the pronunciation in English) is a Gujarati name, (at least one) meaning Tiny.
>I know both he and Gandhi were Gujarati but your mention of the name got me googling around a bit to refresh what small knowledge I have of India and Indian history ( which I confess comes more from studying the Raj than from actually studying Indian history )
Yes both were Gujarati like me and the Patels. Patels are Patels, Lohanas are Thakers, Vaniyas are Sheth. Gandhiji was a Vaniya, specifically Vasihnav Vaniya, ie. his Gods are what we have but belonging to the Vaniya caste/community. The other branch is Jain Vaniya who have Buddha / Mahavir as their Gods.
Though I must disclaim I am not an authority on castes and creeds so the above details may not be accurate.