First of all, if your laptop is really used as a compact desktop at home or at work and in fact doesn't travel much, removing the battery robs you of it functions as a 'UPS'. Solution is to buy a real UPS. For a laptop, you only need a small one (300 to 350VA), these can be found for $40 or less (sometimes even 'free after rebate'), and a UPS is a lot cheaper than using a $200+ lithium battery as a UPS but destroying it over a period of 6 to 24 months in the process.
And the next thing, notwithstanding the general advice to remove a laptop battery that is not needed and not being used, the battery needs to be exercised 2 to 4 times a year. So, once in a while, put it back in the laptop, draw it down to about 25% and then charge it back up to about 60% (or 100% and then back down to 60%; Lithium batteries store better with a less than full charge although in my personal experience I have not found the difference to really matter very much).
And finally, it's probably not a good idea to remove the battery while you are staying in a hotel for a few days, even if you won't need it. The risk of forgetting the battery in the hotel room when you check out is significant and you can mitigate this by leaving the battery in your laptop bag, but ask anyone who uses PC Cards about 'lost dongle cables'.
Also note that lithium batteries have a finite and limited life in terms of the number of charge/discharge cycles. Although this varies by battery model, it's in the low-to-mid hundreds (say 300 to 600 cycles as a typical range). If you really are using your battery while traveling, charging and discharging it on a daily basis, this fact will 'get you' no matter what you do. But, more commonly, people find that they have destroyed their battery without ever really using it, by leaving it in the laptop while the laptop was plugged in continuously. And we have already covered the solution to that problem.
One last comment, given the price of laptop batteries, it's worth noting that some extended warranty covers the batteries. If you are really going to be using the battery heavily (see the previous paragraph), this may be worth taking into consideration when the colored shirt guy at Buy More offers you an extended warranty at the time of the laptop purchase. Find out if the battery is covered, and if your use pattern is such that you will probably be going through more than the initial battery over the course of the extended warranty, maybe you are in one of those situations in which an extended warranty really does make sense.