I was excited to see a new version of the plugin, but didn't luck out.  I was 
hoping
it would let me specify a jetty config file, so that I could do the following:

http://docs.codehaus.org/display/JETTY/Files+locked+on+Windows

You can do the following: extract the runjettyrun_1.0.1.jar in the eclipse 
plugin
directory, then extract the jetty-6.1.6.jar in the lib directory. Edit the file
org\mortbay\jetty\webapp\webdefault.xml and change the "useFileMappedBuffer" to
false. It should look like the following:

    <init-param>
      <param-name>useFileMappedBuffer</param-name>
      <param-value>false</param-value>
    </init-param>  

Then pack the jetty-6.1.6.jar and the runjettyrun_1.0.1.jar again. You can use 
a zip
program for the packing.

It would be very nice if we didn't need to follow hanstchel's steps to have 
Jetty 
not locking CSS and Javaspript files . . .

Is there any time frame on this being fixed without doing the steps above?

As a side note, we tried these steps with Eclipse 3.3, RJR 1.0.1, and Tapestry
5.0.14.  The steps above did not work.

Changing the webdefault.xml in the plugin package didn't worked for me either.

It worked for after also editing the file at
eclipse/configuration/**/jetty-6.jar/webdefault.xml. I belive that doing a 
eclipse
-clean will have the same effect.

I found another way, that may or may not be easier.
It surely is less intrusive.

Since run-jetty-run loads the webdefault.xml from the classpath, just make sure 
that
your webdefault.xml is located in the expected package and contained in the 
classpath
before the run-jetty-run libraries.

So having a org/mortbay/jetty/webapp/webdefault.xml in my projects classpath 
allowed
my to apply my own webdefault.xml.

But how will you make sure it will look for your webdefault.xml before the 
plugin's?

The order of the classpath entries determines that.
When searching for a resource, the classpath entries are iterated in the order 
they
were defined.

In the classpath tab of the "Run configurations" dialog you can make sure that 
the
entry containing your webdefault.xml is placed before the run-jetty-run 
libraries.

FWIW, version 1.1 has been released, and substantially changes the class path 
used, 
which may invalidate the workarounds described in the earlier comments.

Old summary: File locking on windows
New summary: Disable Jetty's locking of static files

Issue 17 has been merged into this issue.

I used stevend's method and it worked like a charm.  For some reason I got 
errors when 
trying to launch after repacking the jars (I'm using Spring STS instead of a 
stock 
standard Eclipse install)

The simple method that works for me is to add this configuration snippet to 
web.xml:

    <servlet>
        <servlet-name>default</servlet-name>
        <init-param>
            <param-name>useFileMappedBuffer</param-name>
            <param-value>false</param-value>
        </init-param>
    </servlet>

Sasa

I think James fix this in r55 and now in Jetty 1.2 .

This still happens using 

<plugin>
    <groupId>org.mortbay.jetty</groupId>
    <artifactId>jetty-maven-plugin</artifactId>
    <version>7.4.5.v20110725</version>
</plugin>

errrr, maven-jetty-plugin is not part of RunJettyRun...