There is a 45 (edit: originally said 30 icons which of course is the old cap) icon 'hard limit to the amount of maintaned spells which are visible to a player BUT players can obviously have more than 30 buffs on them at once or raid buffing would basically be rendered useless (i.e., trust me, tanks get more than 30 buffs in a guild raid)

Looking at it another way - if there was a buff limit, can you imagine the nightmare of working out which buffs to put on who to hit but not exceed a cap??? Be a shocker and a half - not to mention all the proccing buffs

To reiterate - there is no limit to the amount of buffs on a char but a limit (45) on how many icons you see

Edit: Quoted 30 as the hard cap - that is the old one - the new one is 45 icons