President Jammeh has lost the plot completely. In a recent statement condemning gay people he ordered them to leave the country and threatened to "cut off the head" of any gay person found in The Gambia, according to the BBC's report. This isn't a good position to be in for the leader of a country heavily dependent on North European beach tourists – there must be hundreds, if not thousands of gay tourists, expats and NGOs in The Gambia at any one time.
Although most African countries inherited the archaic laws banning homosexuality left by their respective colonial governments, most have used them very rarely. For a tourism-dependent government to scare airlines and tour operators like this – not to mention their own people – is the height of folly. But perhaps that shouldn't surprise us in The Gambia's case. The British foreign office has yet to respond on their travel advice page - the limit of their advice to gay people on their Gambia page is "Homosexuality is illegal in The Gambia." Their LGBT page is more useful.
In practice, despite what Jammeh says, gay visitors should not have any problems at all in the country. Certainly at Rough Guides we've never heard of any hassle (and the advice in the book is that you should experience no problems) – though it's hard now not to advise gay visitors to keep a very low profile and completely avoid local relationships. And if you're worried that your circumstances might cause you problems, you should definitely register with your embassy via their website.