Of these two device types, smartphones have been around longer. They've traditionally been a high-end sale, and that market is reaching saturation (as are 3G networks). We're likely to see lower-cost smartphones emerging as suppliers try to enlarge the market. The upshot is that mobile apps are going to be a permanent feature of our lives and enhanced information services are going to be taken for granted by customers.
I wouldn't want to take bets on the tablet market. Apple's achievement with the iPad is remarkable but I guess we'd all feel more comfortable if it had some serious competitors. I'll be watching Amazon's progress with interest here – just as I'll be keeping an eye on Google.