I'm not a experienced investor per se, but I think that the main advantage in this stock split is basically a mathmatical matter. Even if the "market value" of the stock is split in two, the idea is that any gains after the split will necessarily be multipled by two. Ie, 1 pt gain X 1 share = $1 dollar gain. 1 pt gain X 2 shares = $2 dollar gain. There is no reason to believe that gains on the post-split shares will also necessarily be divided by a factor of in half.
Market value should increase by a factor of 2 when twice as many shares are owned.
(example: I own DUK (any energy stock). Its gained 15% since this time last year. If it had split at that time, I would have twice as much gain.) Would appreciate your comments on my analysis Kaz-modan.
With a stock like ABT I beleive the split will put shares above 1,000,000,000, this shows quite a bit of support from the investment world and the public will be much more likely to buy something at $40 as opposed to $80. Give it another year you may see the split again or more likely a large buy back from the company.