I have just dusted off my druid, and from what I remember str was good for both cat and bear dps. Has this changed to agility for cat?

It depends on your total AP and chance to crit.

In general 1 pt str > 1 pt agi for overall dps until AP >900-1000.

Note however that agility also increase AC and dodge, so dps may not be your only concern.

For pure DPS, str is always going to be better than agi until you get into some sick AP. If you pvp, burst damage is king, so having a high agi is really important. But for PvE, go all out on str.