Hi,
I don't suppose it would be possible for Textmate to make an attempt to 'guess' the tab size (and whether the file is using hard/soft tabs) when a file is opened? I often wind up editing other people's code and, usually, they wind up using something other than 'soft tabs: 2'. So I regularly have to fiddle with the tab size to make things match up nicely.
ISTR a previous editor I've used, WingIDE[1], having this feature, and it was really handy... And no, that's not an 'every other editor does it' -- it's the only time I've seen that feature, but it was really useful!
Oh, even better! I'm looking at the code for Typo just now, and it's not even consistent throughout the code! In fact most of it is 'soft tabs: 2', just views/articles/taglist.rhtml (the first one I happened to want to edit) that's using hard tabs...