Can I get Memcached running on a Windows (x64) 64bit environment?

Memcached 1.4.5 binary for win x64 can be found here: http://downloads.northscale.com/memcached-1.4.5-amd64.zip

Another option would be to install Couchbase Server 1.8.0 x64 from here: http://www.couchbase.com/download, the bundled memcached seems to be version 1.7.1.1 (sounds like an internal version, I can't tell which is the real one)

As for running memcached as a service, this tutorial might be enough:

http://www.richardnichols.net/2010/08/install-memcached-on-windows-server/

North Scale labs have released a build of memcached 1.4.4 for Windows x64:

http://blog.couchbase.com/memcached-windows-64-bit-pre-release-available

http://labs.northscale.com/memcached-packages/

UPDATE: they have recently released Memcached Server - still FREE but enhanced distro with clustering, web-based admin/stats UI etc. (I'm not related to them in any way) Check it out at http://northscale.com/products/memcached.html and download at: http://www.northscale.com/download.php?a=d

UPDATE 2: NorthScale Memcached is no longer available as a standalone download. Now they have made it part of their commercial No-SQL DB offering called Membase. It can be configured to run in Memcached-only mode (i.e. without persistence) and there's a 100% free version too. Check it out here: http://www.membase.org/downloads

UPDATE 3: MemBase has slept with CouchDB and produced a hybrid product offering, called CouchBase. They still do offer a free "Community" version at http://www.couchbase.com/download

Up-to-date Binaries

NorthScale has really old versions (the newest is 1.4.5 which is from April 2010) but there's a guy who offers 64-bit Memcached binaries for Windows compiled using Cygwin (but they don't require it installed) in his GitHub repository github.com/nono303/memcached.

For example, the binaries of the most recently released version (as of writing this answer) 1.5.16 are here. There're both 32 and 64-bit versions.

Memcached as a Windows Service

If you want to install it as a Windows service, you can use for example the open-source Non-Sucking Service Manager:

nssm install memcached c:\path\to\memcached.exe
nssm start memcached

See the documentation for details.

Just so people know, the 32-bit and 64-bit version as build by the good people from membase/couchbase/whatever is still available the blog URL has changed though:

32-bit binary of memcached 1.4.4 as Windows-service:

http://blog.couchbase.com/memcached-144-windows-32-bit-binary-now-available

http://s3.amazonaws.com/downloads.northscale.com/memcached-win32-1.4.4-14.zip

64-bit binary of memcached 1.4.4 as Windows-service:

http://blog.couchbase.com/memcached-windows-64-bit-pre-release-available

http://s3.amazonaws.com/downloads.northscale.com/memcached-win64-1.4.4-14.zip

The 64-bit version does have the wrong uptime.

So maybe you want this binary of 1.4.2 instead:

http://www.urielkatz.com/archive/detail/memcached-64-bit-windows/

The 32-bit version as included with MemCacheDManager also suppors running on Windows 2000 (no IPv6):

http://allegiance.chi-town.com/MemCacheDManager.aspx http://allegiance.chi-town.com/Download.aspx?dl=Releases/MemCacheDManager_1_0_3_0.msi&rurl=MemCacheDManager.aspx

To unpack the msi:

msiexec /a Releases_MemCacheDManager_1_0_3_0.msi /qb TARGETDIR=c:\memcached