why do people call the Philippines "the" Philippines and not just Philippines?

Sample usage:
The Spratly Islands consist of more than 100 small islands or reefs.
They are surrounded by rich fishing grounds and potentially by gas and
oil deposits. They are claimed in their entirety by China, Taiwan, and
Vietnam, while portions are claimed by Malaysia and "the" Philippines.
--- cia.gov

Whats with the "the" in the "the Philippines".

It is simply traditional usage.  With island groups quite common, the
Orkneys, the Hebrides, and logical since one is referring to a group,
and, I believe, using an article was earlier common for areas,  "the
Lebanon", maybe from a time when it was not a country but only an area
of the Middle East.  And we still speak of the Netherlands, again a
plural.
This usage may have dropped out of favor in modern, telegraph-like speech.

Some of the information in this answer may be of interest:

http://www.answers.google.com/answers/threadview?id=319841

The name is structurally a plural count-noun. A native English-speaker
can "feel" that it refers to multiple islands. What confuses the issue
is that the same name, without inflection, also gets used when a
non-count sense is "felt." Very similar to "The Netherlands" and "The
United States"; but the latter two names are more often used in a
non-count sense than in their original count-noun sense. If English
employed inflectional differences to keep the count and non-count
senses separate, it would be less confusing. For example, we say
"Indonesia" to refer to "the whole region that is filled with the
[discrete] Indonesian Islands." If we did this for the Philippines, we
would say that "Philippinia" was "the whole region comprising the
[discrete] Philippine Islands." But alas, instead of "Philippinia," we
just use the count-sense structure to stand for the non-count-sense
meaning.

You learn something every day.  Pinkfreud's reference really settles
the matter, I think, worth the mullah for remembering or finding it.
Reading German, I am still surprised when the UN and USA (in German)
are followed by a verb in the plural form, which is completely
correct.  The English go the other way, sometimes using a plural verb
with a singular noun that is a collective, parliament, for example.
And jack_of_few_trades-ga, who just  - after 12 months -  added a
comment to the qustion Pink referenced, makes an interesting  - but
explainable point:  "going to court" is going to the institution and
presumably being involved in its proceedings.  "Going to the court" is
going to the physical edifice, to the courthouse, as in the answer,
the noun "house" having been dropped.
I don't know about "the 101" in California.  I always say "route 101"
and people look at me funny.  But there is no explaining the way
people talk in Southern California (except my sister.  Have to ask
her.)

I'm a denizen of this country right now, I believe "the Philippines"
is called as such because a more expanded way to call my country would
be "The Philippine Islands" ('Philippine' without the 's' becomes an
adjective). To make it shorter, it's just called "The Philippines."
It's probably done in the same way as you would shorten the "special
units" as "the specials." Or it's used in the same way as The Azores,
The Hebrides. I think even "the United States" is a name that
qualifies being under this rule.

Oh was I 12 months late?  Silly me, thanks for pointing that out
Myoarin... I rarely check the dates, just follow the links blindly :)

Maybe it's a shortened version of 'Republic of the Philippines' (?)