I was going to update the documentation, but decided to test a little more thoroughly as to what is and is not actually invalidated when you add a vertex. Here are the somewhat surprising results:

<vecS, vecS, undirectedS> - nothing invalidated
<vecS, vecS, directedS> - edge iterators are invalidated, nothing else
<vecS, vecS, bidrectionalS> - nothing invliadated

The test file is in trunk at libs/graphs/test/adj_list_invalidaton.cpp. It's not comprehensive, but will segfault as indicated above.