TeX Live has added a managing program since 2008, tlmgr. This program can't be used for updating from a release to a new one, up to now. But this is not a disadvantage in all respects.
The TeX Live trees are rooted in /usr/local/texlive (changeable at installation time) and each release is put in a "year" directory: /usr/local/texlive/2010 for the last one, /usr/local/texlive/2011 for the next.
My suggestion is always to avoid the option to create symbolic links for the binaries in the system directories (/usr/bin or /usr/local/bin) and to prefer adding
/usr/local/texlive/2011/bin/<...>
(where <...> stands for the architecture) to the PATH variable.
Suppose one is working to a major project which is compiling well on TeX Live 2010, but breaks with 2011 because of some updates to important packages (it happens). In this case it's very easy to go back to 2010: all it's needed is to change the PATH.
I actually suggest to make a symbolic link, say /opt/texbin pointing to the binaries
ln -s /usr/local/texlive/2011/bin/<...> /opt/texbin
and adding /opt/texbin to PATH. Thus going from a release to another becomes simply redefining the symbolic link (this is, more or less, the approach taken by MacTeX). When we're sure that the new release is working well, we can delete the old one with a single command.
Welcome additions to tlmgr would be the possibility to have this (but there are so many variants in the operating systems to cope with) and also the possibility of seeing with tlmgr(2010) the presence of tlmgr(2011) offering the option to install the new release. But not simply changing 2010 into 2011 and overwriting the old release: disk space is quite cheap, nowadays.
intersectionsyntax doesn't work in 2.10. Maybe I misunderstood? – Seamus Jul 01 '11 at 10:18