Much as I do like the Lonely Planet books on the whole, they do get a little out of date especially in countries developing as quickly as Cambodia. Prices change, infrastructures improve, new things appear. Very briefly, though – and relevant up to the date posted – here are some things that might be useful to anyone visiting in the near future.
The entry visa-on-arrival at Siem Reap (and I assume Phnomh Penh) International Airport is $20 for UK citizens (and most others, I believe) and payment has to be in US Dollars. A single passport photo is required. You get 30 days by default. Conveniently, an ATM is available before you reach the visa counter so you can withdraw the cash should you need it. Ensure you have a full page in your passport for the visa and space for the accompanying stamps. One girl I met on the plane had to pay an extra $10 (she haggled down from $20!) for the immigration officer to paste the Cambodian visa over the Chinese one in her US passport. Note that the last handful of pages in the US passport are not supposed to be used for visas, so the guy was within his rights (although a Laos border official had gone ahead and used one of the pages regardless and for no fee).
You can also organise a visa in advance in most surrounding countries, or even online, though this incurs a $5 handling fee and the only thing you’ll save is a bit of time. You’ll also have to email them a suitable passport photo so it all seemed a little fiddly to me. My experience at the airport was one of fairly good efficiency.
International departure tax from the airports is $25, again payable in Dollars.
Internet access if widespread with Wi-Fi even making an appearance in some areas. It’s usually free for users of bars or cafes, though I’m sure some guest houses and hotels also have it. Standard internet cafes are all over the place and vary in price from $0.50 to $1.50 an hour in my experience. The connection speed also varies from shop to shop.
ATMs are common and accept various well-known cards. I’ve used two different ones so far, both take Visa, both dispense US Dollars and neither charged me a fee. I have been told that some ATMs dispense Riel, but in honesty dollars are better. The best way to get Riel is to spend dollars and get them as change. The official exchange rate at a bank is around 3990 Riel to the dollar, but every single shop or individual I have dealt with has rounded this up to 4000 to make calculations nice and simple.
There are many charitable foundations in Cambodia, though I’m sure some of the ones you’ll see are – unfortunately – dodgy. I hope these are in the minority. Check out any before you devote time or money to them. The worthwhile ones are all well worth any of your efforts and dollars. As with any country like this, don’t hand out cash to beggars. If you want to help, donate to a charity. If the people are genuine, they can get help from there.