Picture of wobbly vs less-wobbly 9800
At the risk of beating the "wiggling" discussion to death I've posted a pic which shows the difference between the devices. I'm hoping this might help someone when they go to a store to test drive the units.
Both are Mexico 5 with a build date 3 weeks later for the one on the left which makes me suspect their quality is improving as the manufacturing continues.
You can see the one on the left has the bottom lip of the slider relatively tight against the base of the phone...kind of like a hand in a glove to use that metaphor. This is the non-wiggling one.
The device on the right has the slider raised up and it is not recessed into the bottom part of the phone.
Now having said that, both phones have some wiggle. The difference being that the one on the right has much more wiggle to it. You can also feel more restriction in the sliding mechanism with the left one i.e. it feels tight. Whether this will loosen up over time - who knows.
I should also state that the unit on the right isn't that bad and some may even prefer it as the slider moves more quickly when opening. To me it really is almost a coin toss as both are good devices although I'm going to keep the one on the left in the hopes that it won't loosen up further.
Hope this helps future purchasers.