php throws an E_NOTICE:
PHP Notice:  MemcachePool::get(): Failed to uncompress data

Can you try using trunk please? I can't reproduce it with memcache 1.2.8 and pecl's trunk (did not try using last release).

or using the NON_BLOCKING_IO branch

test script:
<?php
error_reporting(E_ALL & E_STRICT);  
ini_set("display_errors", "stderr");
$memcache_obj = memcache_connect('10.55.1.6', 11211);
memcache_set($memcache_obj, 'test123112', 1, MEMCACHE_COMPRESSED, 30);
$ret = memcache_get($memcache_obj, 'test123112');
var_dump($ret);
?>

PHP 5.2.10
Tested on memcached 1.2.6 and memcached 1.4.4

pecl-memcache 3.0.2 test script result: string(1) "1"
server ~ # strace -e send,recv php membug_test.php 
send(3, "set test123112 0 10 1\r\n1\r\n", 26, 0) = 26
recv(3, "STORED\r\n", 32768, 0)         = 8
send(3, "get test123112\r\n", 16, 0)    = 16
recv(3, "VALUE test123112 0 1\r\n1\r\nEND\r\n", 32768, 0) = 30
string(1) "1"

pecl-memcache 3.0.4
pecl-memcache 3.0.5-dev ($Revision: 296729 $)
server ~ # strace -e send,recv php membug_test.php 
send(3, "set test123112 770 10 1\r\n1\r\n", 28, MSG_NOSIGNAL) = 28
recv(3, "STORED\r\n", 32768, 0)         = 8
send(3, "get test123112\r\n", 16, MSG_NOSIGNAL) = 16
recv(3, "VALUE test123112 770 1\r\n1\r\nEND\r\n", 32768, 0) = 32
bool(false)

If we disable compressing all work fine
- memcache_set($memcache_obj, 'test123112', 1, MEMCACHE_COMPRESSED, 30);
+ memcache_set($memcache_obj, 'test123112', 1, 0, 30);

pecl-memcache 3.0.5-dev ($Revision: 296729 $)
server ~ # strace -e send,recv php membug_test.php 
send(3, "set test123112 768 10 1\r\n1\r\n", 28, MSG_NOSIGNAL) = 28
recv(3, "STORED\r\n", 32768, 0)         = 8
send(3, "get test123112\r\n", 16, MSG_NOSIGNAL) = 16
recv(3, "VALUE test123112 768 1\r\n1\r\nEND\r\n", 32768, 0) = 32
int(1)

Last week I hit this bug when testing Redhat RHEL-6 Beta.

I developed a patch that fixes this issue.  The patch can be
found in Redhat Bugzilla at https://bugzilla.redhat.com/show_bug.cgi?id=638892

Thank you all for your example scripts and previous research of this issue; both helped a lot to develop the fix.

This bug has been fixed in SVN.

In case this was a documentation problem, the fix will show up at the
end of next Sunday (CET) on pecl.php.net.

In case this was a pecl.php.net website problem, the change will show
up on the website in short time.
 
Thank you for the report, and for helping us make PECL better.