That was hardly an easy win for Federer, hell, like it was said above, he didnt even break Roddick till 14-14 in the Fifth set. Roddick played one of the best matches of his life and if he hadnt choked away the 2nd, he probably wouldve won the match.
As for the longest 5th set ever, I'm pretty sure I've seen at least one end up in the 20s, but I could be wrong.
Wimbledon in 2007, Marcelo Melo/André Sá beat Paul Hanley/Kevin Ullyett 5–7, 7–6(4), 4–6, 7–6(7), 28–26.
It was, however, the longest match in terms of number of games played since the tiebreaker started being used.