added ebuild for nexus 2.10. it has not been tested yet.

dev-java/nexus-oss-bin/Manifest

@@ -0,0 +1,3 @@
+AUX init.sh 419 SHA256 11617fd995b9d17dbaee7421b315a5bddc5861a8e9a8e522e5d4445f2357ec1e SHA512 2ce7a5b3f396865551f0d35efa7a10ff4b4e396095066043b028316e859c7b3fca6c4035d224ad9260a5db1e3e1bf92416ea6c13b67ff8cc18ebdb0b91265300 WHIRLPOOL 1cc82a03d026bb959aefc2ee2b6ea0b80102e15654398d4609f63d3ce4b8ebc6310740628707aaddadb4f062f767ddd6c8caef937f87630b85096d1207df987b
+DIST nexus-2.10.0-02-bundle.tar.gz 50071813 SHA256 730442be2ca4918b44a69b98bb62abfcbf8ce8f997385349510dd807c1bf88d6 SHA512 22a75a71d279b34ad2c43c4360a5fcf6218494ab3772e7419a6817e86ee8682843402a727c720d410e79e0015dddd63a38049afddeb20dfb8a7860fa3bf057e2 WHIRLPOOL d025400ff050744a4632c6f30a7708ae912506dc9e924adccf73ce1ababeaf99c701b57ea9594370a71dbf41d8cc91917cbcbb3dada360f1eb990796923b8ea2
+EBUILD nexus-oss-bin-2.10.0.ebuild 1059 SHA256 d3c162464218231bfee1a00470fd7cd7b3b9a4626df742052f236796b711b322 SHA512 b3016fcf79812e2d08b9dbd6a11a286f276ecf9812a1761c473da5a158ad663c2ca3a4372dd42d548da77996f296501129fcf00717565dccbc9f99d6ac7108b7 WHIRLPOOL fb30bc08ce4d87a30ef317fc34a05dceba3fb04954e0f063fc0f64a91f8f79fbc8168b6fedf87dbb023695300e40447d1046d35a03536c2e7cac67a539f9d889

dev-java/nexus-oss-bin/files/init.sh

@@ -0,0 +1,26 @@
+#!/sbin/runscript
+
+depend() {
+    need net
+    use dns logger
+}
+
+RUN_AS=nexus
+
+checkconfig() {
+    return 0
+}
+
+start() {
+    checkconfig || return 1
+
+    ebegin "Starting ${SVCNAME}"
+    su $RUN_AS -c "/opt/nexus/nexus-oss-webapp/bin/jsw/linux-x86-32/wrapper start"
+    eend $?
+}
+
+stop() {
+    ebegin "Stopping ${SVCNAME}"
+    su $RUN_AS -c "/opt/nexus/nexus-oss-webapp/bin/jsw/linux-x86-32/wrapper stop"
+    eend $?
+}

dev-java/nexus-oss-bin/nexus-oss-bin-2.10.0.ebuild

@@ -0,0 +1,45 @@
+inherit eutils user
+
+DESCRIPTION="Maven Repository Manager"
+HOMEPAGE="http://nexus.sonatype.org/"
+LICENSE="GPL-3"
+SUB_VERSION="-02"
+#SRC_URI="http://www.sonatype.org/downloads/nexus-${PV}-02-bundle.zip"
+SRC_URI="http://download.sonatype.com/nexus/oss/nexus-${PV}${SUB_VERSION}-bundle.tar.gz"
+RESTRICT="mirror"
+KEYWORDS="~x86 ~amd64"
+SLOT="0"
+IUSE=""
+
+S="${WORKDIR}"
+
+RDEPEND=">=virtual/jdk-1.6"
+
+INSTALL_DIR="/opt/nexus"
+
+WEBAPP_DIR="${INSTALL_DIR}/nexus-oss-webapp"
+
+pkg_setup() {
+    #enewgroup <name> [gid]
+    enewgroup nexus
+    #enewuser <user> [uid] [shell] [homedir] [groups] [params]
+    enewuser nexus -1 /bin/bash /opt/nexus "nexus"
+}
+
+src_unpack() {
+    unpack ${A}
+    cd "${S}"
+
+#    epatch "${FILESDIR}/${P}.patch"
+}
+
+src_install() {
+    insinto ${WEBAPP_DIR}
+    doins -r nexus-${PV}${SUB_VERSION}/*
+
+    newinitd "${FILESDIR}/init.sh" nexus
+
+    fowners -R nexus:nexus ${INSTALL_DIR}
+    fperms 755 "${INSTALL_DIR}/nexus-oss-webapp/bin/jsw/linux-x86-64/wrapper"
+    fperms 755 "${INSTALL_DIR}/nexus-oss-webapp/bin/jsw/linux-x86-32/wrapper"
+}