They have gone up about $7 to hit $15 from 2008. With fuel prices this high its difficult for any airline to make considerable money.
They have started code sharing on a limited basis, I think once the rumored perks package is offered and Airmiles discontinued so they can better integrate with some airlines then you might see the stock get to $20ish but I think for the forseeable future the $15-17 range is most like with a possible drop back to $12ish.
The other next big leap will be to us buisness markets - Calgary - IAH is a perfect market. At the momeny the no biz class and frequent flyer program makes this a no go, I think they can make a go of it if they slightly change their inflight offerings for US biz markets and start a FFP - I dont see that happening anytime soon though.
I have heard rumors they have been looking at buying Transat - not sure if that would be a good thing of a bad thing
I have invested 2 different times in westjet, once I made out great buying at $10 selling at $23, the next I bought at $11 and have held it for a while now. If you like airlines then sure invest, if you are looking to get maximum ROI then dont invest in airlines.